5
OurconceptionofthenatureofOdoursmustbeanalogoustothatofSavours；inasmuchastheSapidDryeffectsinairandwateralike，butinadifferentprovinceofsense，preciselywhattheDryeffectsintheMoistofwateronly。WecustomarilypredicateTranslucencyofbothairandwaterincommon；butitisnotquatranslucentthateitherisavehicleofodour，butquapossessedofapowerofwashingorrinsing[andsoimbibing]theSapidDryness。
FortheobjectofSmellexistsnotinaironly：italsoexistsinwater。Thisisprovedbythecaseoffishesandtestacea，whichareseentopossessthefacultyofsmell，althoughwatercontainsnoair（forwheneverairisgeneratedwithinwateritrisestothesurface），andthesecreaturesdonotrespire。Hence，ifoneweretoassumethatairandwaterarebothmoist，itwouldfollowthatOdouristhenaturalsubstanceconsistingoftheSapidDrydiffusedintheMoist，andwhateverisofthiskindwouldbeanobjectofSmell。
ThatthepropertyofodorousnessisbasedupontheSapidmaybeseenbycomparingthethingswhichpossesswiththosewhichdonotpossessodour。Theelements，viz。Fire，Air，Earth，Water，areinodorous，becauseboththedryandthemoistamongthemarewithoutsapidity，unlesssomeaddedingredientproducesit。Thisexplainswhysea—waterpossessesodour，for[unlike’elemental’water]itcontainssavouranddryness。Salt，too，ismoreodorousthannatron，astheoilwhichexudesfromtheformerproves，fornatronisalliedto[’elemental’]earthmorenearlythansalt。Again，astoneisinodorous，justbecauseitistasteless，while，onthecontrary，woodisodorous，becauseitissapid。Thekindsofwood，too，whichcontainmore[’elemental’]waterarelessodorousthanothers。
Moreover，totakethecaseofmetals，goldisinodorousbecauseitiswithouttaste，butbronzeandironareodorous；andwhenthe[sapid]moisturehasbeenburntoutofthem，theirslagis，inallcases，lessodorousthemetals[thanthemetalsthemselves]。Silverandtinaremoreodorousthantheoneclassofmetals，lesssothantheother，inasmuchastheyarewater[toagreaterdegreethantheformer，toalessdegreethanthelatter]。
SomewriterslookuponFumidexhalation，whichisacompoundofEarthandAir，astheessenceofOdour。[IndeedallareinclinedtorushtothistheoryofOdour。]HeraclitusimpliedhisadherencetoitwhenhedeclaredthatifallexistingthingswereturnedintoSmoke，thenosewouldbetheorgantodiscernthemwith。Allwritersinclinetoreferodourtothiscause[sc。exhalationofsomesort]，butsomeregarditasaqueous，othersasfumid，exhalation；whileothers，again，holdittobeeither。Aqueousexhalationismerelyaformofmoisture，butfumidexhalationis，asalreadyremarked，composedofAirandEarth。Theformerwhencondensedturnsintowater；
thelatter，inaparticularspeciesofearth。Now，itisunlikelythatodouriseitherofthese。Forvaporousexhalationconsistsofmerewater[which，beingtasteless，isinodorous]；andfumidexhalationcannotoccurinwateratall，though，ashasbeenbeforestated，aquaticcreaturesalsohavethesenseofsmell。
Again，theexhalationtheoryofodourisanalogoustothetheoryofemanations。If，therefore，thelatterisuntenable，so，too，istheformer。
ItisclearlyconceivablethattheMoist，whetherinair（forair，too，isessentiallymoist）orinwater，shouldimbibetheinfluenceof，andhaveeffectswroughtinitby，theSapidDryness。Moreover，iftheDryproducesinmoistmedia，i。e。waterandair，aneffectasofsomethingwashedoutinthem，itismanifestthatodoursmustbesomethinganalogoustosavours。Nay，indeed，thisanalogyis，insomeinstances，afact[registeredinlanguage]；forodoursaswellassavoursarespokenofaspungent，sweet，harsh，astringentrich[=’savoury’]；andonemightregardfetidsmellsasanalogoustobittertastes；whichexplainswhytheformerareoffensivetoinhalationasthelatteraretodeglutition。Itisclear，therefore，thatOdourisinbothwaterandairwhatSavourisinwateralone。ThisexplainswhycoldnessandfreezingrenderSavoursdull，andabolishodoursaltogether；forcoolingandfreezingtendtoannulthekineticheatwhichhelpstofabricatesapidity。
TherearetwospeciesoftheOdorous。Forthestatementofcertainwritersthattheodorousisnotdivisibleintospeciesisfalse；itissodivisible。Wemustheredefinethesenseinwhichthesespeciesaretobeadmittedordenied。
Oneclassofodours，then，isthatwhichrunsparallel，ashasbeenobserved，tosavours：toodoursofthisclasstheirpleasantnessorunpleasantnessbelongsincidentally。ForowingtothefactthatSavoursarequalitiesofnutrientmatter，theodoursconnectedwiththese[e。g。thoseofacertainfood]areagreeableaslongasanimalshaveanappetiteforthefood，buttheyarenotagreeabletothemwhensatedandnolongerinwantofit；noraretheyagreeable，either，tothoseanimalsthatdonotlikethefooditselfwhichyieldstheodours。Hence，asweobserved，theseodoursarepleasantorunpleasantincidentally，andthesamereasoningexplainswhyitisthattheyareperceptibletoallanimalsincommon。
Theotherclassofodoursconsistsofthoseagreeableintheiressentialnature，e。g。thoseofflowers。Forthesedonotinanydegreestimulateanimalstofood，nordotheycontributeinanywaytoappetite；theireffectuponit，ifany，israthertheopposite。FortheverseofStrattisridiculingEuripides—
Usenotperfumerytoflavoursoup，containsatruth。
Thosewhonowadaysintroducesuchflavoursintobeveragesdeforceoursenseofpleasurebyhabituatingustothem，until，fromtwodistinctkindsofsensationscombined，pleasurearisesasitmightfromonesimplekind。
Ofthisspeciesofodourmanaloneissensible；theother，viz。thatcorrelatedwithTastes，is，ashasbeensaidbefore，perceptiblealsototheloweranimals。Andodoursofthelattersort，sincetheirpleasureablenessdependsupontaste，aredividedintoasmanyspeciesastherearedifferenttastes；butwecannotgoontosaythisoftheformerkindofodour，sinceitsnatureisagreeableordisagreeableperse。Thereasonwhytheperceptionofsuchodoursispeculiartomanisfoundinthecharacteristicstateofman’sbrain。
Forhisbrainisnaturallycold，andthebloodwhichitcontainsinitsvesselsisthinandpurebuteasilycooled（whenceithappensthattheexhalationarisingfromfood，beingcooledbythecoldnessofthisregion，producesunhealthyrheums）；thereforeitisthatodoursofsuchaspecieshavebeengeneratedforhumanbeings，asasafeguardtohealth。Thisistheirsolefunction，andthattheyperformitisevident。Forfood，whetherdryormoist，thoughsweettotaste，isoftenunwholesome；whereastheodourarisingfromwhatisfragrant，thatodourwhichispleasantinitsownright，is，sotosay，alwaysbeneficialtopersonsinanystateofbodilyhealthwhatever。
Forthisreason，too，theperceptionofodour[ingeneral]
effectedthroughrespiration，notinallanimals，butinmanandcertainothersanguineousanimals，e。g。quadrupeds，andallthatparticipatefreelyinthenaturalsubstanceair；becausewhenodours，onaccountofthelightnessoftheheatinthem，mounttothebrain，thehealthofthisregionistherebypromoted。Forodour，asapower，isnaturallyheat—giving。ThusNaturehasemployedrespirationfortwopurposes：primarilyfortherelieftherebybroughttothethorax，secondarilyfortheinhalationofodour。Forwhileananimalisinhaling，—odourmovesinthroughitsnostrils，asitwere’fromaside—entrance。’
Buttheperceptionofthesecondclassofodoursabovedescribed[doesnotbelongtoallanimal，but]isconfinedtohumanbeings，becauseman’sbrainis，inproportiontohiswholebulk，largerandmoisterthanthebrainofanyotheranimal。Thisisthereasonofthefurtherfactthatmanalone，sotospeak，amonganimalsperceivesandtakespleasureintheodoursofflowersandsuchthings。
Fortheheatandstimulationsetupbytheseodoursarecommensuratewiththeexcessofmoistureandcoldnessinhiscerebralregion。Onalltheotheranimalswhichhavelungs，Naturehasbestowedtheirdueperceptionofoneofthetwokindsofodour[i。e。thatconnectedwithnutrition]throughtheactofrespiration，guardingagainsttheneedlesscreationoftwoorgansofsense；forinthefactthattheyrespiretheotheranimalshavealreadysufficientprovisionfortheirperceptionoftheonespeciesofodouronly，ashumanbeingshavefortheirperceptionofboth。
Butthatcreatureswhichdonotrespirehavetheolfactorysenseisevident。Forfishes，andallinsectsasaclass，have，thankstothespeciesofodourcorrelatedwithnutrition，akeenolfactorysenseoftheirproperfoodfromadistance，evenwhentheyareveryfarawayfromit；suchisthecasewithbees，andalsowiththeclassofsmallants，whichsomedenominateknipes。Amongmarineanimals，too，themurexandmanyothersimilaranimalshaveanacuteperceptionoftheirfoodbyitsodour。
Itisnotequallycertainwhattheorganiswherebytheysoperceive。Thisquestion，oftheorganwherebytheyperceiveodour，maywellcauseadifficulty，ifweassumethatsmellingtakesplaceinanimalsonlywhilerespiring（forthatthisisthefactismanifestinalltheanimalswhichdorespire），whereasnoneofthosejustmentionedrespires，andyettheyhavethesenseofsmell—unless，indeed，theyhavesomeothersensenotincludedintheordinaryfive。Thissuppositionis，however，impossible。Foranysensewhichperceivesodourisasenseofsmell，andthistheydoperceive，thoughprobablynotinthesamewayascreatureswhichrespire，butwhenthelatterarerespiringthecurrentofbreathremovessomethingthatislaidlikealidupontheorganproper（whichexplainswhytheydonotperceiveodourswhennotrespiring）；whileincreatureswhichdonotrespirethisisalwaysoff：justassomeanimalshaveeyelidsontheireyes，andwhenthesearenotraisedtheycannotsee，whereashard—eyedanimalshavenolids，andconsequentlydonotneed，besideseyes，anagencytoraisethelids，butseestraightway[withoutintermission]fromtheactualmomentatwhichitisfirstpossibleforthemtodoso[i。e。fromthemomentwhenanobjectfirstcomeswithintheirfieldofvision]。
Consistentlywithwhathasbeensaidabove，notoneoftheloweranimalsshowsrepugnancetotheodourofthingswhichareessentiallyill—smelling，unlessoneofthelatterispositivelypernicious。Theyaredestroyed，however，bythesethings，justashumanbeingsare；i。e。ashumanbeingsgetheadachesfrom，andareoftenasphyxiatedby，thefumesofcharcoal，sotheloweranimalsperishfromthestrongfumesofbrimstoneandbituminoussubstances；
anditisowingtoexperienceofsucheffectsthattheyshunthese。
Forthedisagreeableodourinitselftheycarenothingwhatever（thoughtheodoursofmanyplantsareessentiallydisagreeable），unless，indeed，ithassomeeffectuponthetasteoftheirfood。
Thesensesmakingupanoddnumber，andanoddnumberhavingalwaysamiddleunit，thesenseofsmelloccupiesinitselfasitwereamiddlepositionbetweenthetactualsenses，i。e。TouchandTaste，andthosewhichperceivethroughamedium，i。e。SightandHearing。
Hencetheobjectofsmell，too，isanaffectionofnutrientsubstances（whichfallwithintheclassofTangibles），andisalsoanaffectionoftheaudibleandthevisible；whenceitisthatcreatureshavethesenseofsmellbothinairandwater。Accordingly，theobjectofsmellissomethingcommontobothoftheseprovinces，i。e。itappertainsbothtothetangibleontheonehand，andontheothertotheaudibleandtranslucent。HencetheproprietyofthefigurebywhichithasbeendescribedbyusasanimmersionorwashingofdrynessintheMoistandFluid。Suchthenmustbeouraccountofthesenseinwhichoneisorisnotentitledtospeakoftheodorousashavingspecies。
ThetheoryheldbycertainofthePythagoreans，thatsomeanimalsarenourishedbyodoursalone，isunsound。For，inthefirstplace，weseethatfoodmustbecomposite，sincethebodiesnourishedbyitarenotsimple。Thisexplainswhywastematterissecretedfromfood，eitherwithintheorganisms，or，asinplants，outsidethem。Butsinceevenwaterbyitselfalone，thatis，whenunmixed，willnotsufficeforfood—foranythingwhichistoformaconsistencymustbecorporeal—，itisstillmuchlessconceivablethatairshouldbesocorporealized[andthusfittedtobefood]。But，besidesthis，weseethatallanimalshaveareceptacleforfood，fromwhich，whenithasentered，thebodyabsorbsit。Now，theorganwhichperceivesodourisinthehead，andodourenterswiththeinhalationofthebreath；sothatitgoestotherespiratoryregion。Itisplain，therefore，thatodour，quaodour，doesnotcontributetonutrition；that，however，itisserviceabletohealthisequallyplain，aswellbyimmediateperceptionasfromtheargumentsaboveemployed；sothatodourisinrelationtogeneralhealthwhatsavourisintheprovinceofnutritionandinrelationtothebodiesnourished。
Thisthenmustconcludeourdiscussionoftheseveralorgansofsense—perception。
6
Onemightask：ifeverybodyisinfinitelydivisible，areitssensiblequalities—Colour，Savour，Odour，Sound，Weight，ColdorHeat，[Heavinessor]Lightness，HardnessorSoftness—alsoinfinitelydivisible？Or，isthisimpossible？
[Onemightwellaskthisquestion]，becauseeachofthemisproductiveofsense—perception，since，infact，allderivetheirname[of’sensiblequalities’]fromtheverycircumstanceoftheirbeingabletostimulatethis。Hence，[ifthisisso]bothourperceptionofthemshouldlikewisebedivisibletoinfinity，andeverypartofabody[howeversmall]shouldbeaperceptiblemagnitude。
Foritisimpossible，e。g。toseeathingwhichiswhitebutnotofacertainmagnitude。
Sinceifitwerenotso，[ifitssensiblequalitieswerenotdivisible，paripassuwithbody]，wemightconceiveabodyexistingbuthavingnocolour，orweight，oranysuchquality；accordinglynotperceptibleatall。Forthesequalitiesaretheobjectsofsense—perception。Onthissupposition，everyperceptibleobjectshouldberegardedascomposednotofperceptible[butofimperceptible]
parts。Yetitmust[bereallycomposedofperceptibleparts]，sinceassuredlyitdoesnotconsistofmathematical[andthereforepurelyabstractandnon—sensible]quantities。Again，bywhatfacultyshouldwediscernandcognizethese[hypotheticalrealthingswithoutsensiblequalities]？IsitbyReason？ButtheyarenotobjectsofReason；nordoesreasonapprehendobjectsinspace，exceptwhenitactsinconjunctionwithsense—perception。Atthesametime，ifthisbethecase[thattherearemagnitudes，physicallyreal，butwithoutsensiblequality]，itseemstotellinfavouroftheatomistichypothesis；forthus，indeed，[byacceptingthishypothesis]，thequestion[withwhichthischapterbegins]mightbesolved[negatively]。Butitisimpossible[toacceptthishypothesis]。OurviewsonthesubjectofatomsaretobefoundinourtreatiseonMovement。
ThesolutionofthesequestionswillbringwithitalsotheanswertothequestionwhythespeciesofColour，Taste，Sound，andothersensiblequalitiesarelimited。Forinallclassesofthingslyingbetweenextremestheintermediatesmustbelimited。Butcontrariesareextremes，andeveryobjectofsense—perceptioninvolvescontrariety：
e。g。inColour，WhitexBlack；inSavour，SweetxBitter，andinalltheothersensiblesalsothecontrariesareextremes。Now，thatwhichiscontinuousisdivisibleintoaninfinitenumberofunequalparts，butintoafinitenumberofequalparts，whilethatwhichisnotpersecontinuousisdivisibleintospecieswhicharefiniteinnumber。Sincethen，theseveralsensiblequalitiesofthingsaretobereckonedasspecies，whilecontinuityalwayssubsistsinthese，wemusttakeaccountofthedifferencebetweenthePotentialandtheActual。Itisowingtothisdifferencethatwedonot[actually]seeitsten—thousandthpartinagrainofmillet，althoughsighthasembracedthewholegrainwithinitsscope；anditisowingtothis，too，thatthesoundcontainedinaquarter—toneescapesnotice，andyetonehearsthewholestrain，inasmuchasitisacontinuum；buttheintervalbetweentheextremesounds[thatboundthequarter—tone]
escapestheear[beingonlypotentiallyaudible，notactually]。So，inthecaseofotherobjectsofsense，extremelysmallconstituentsareunnoticed；becausetheyareonlypotentiallynotactually[perceptiblee。g。]visible，unlesswhentheyhavebeenpartedfromthewholes。Sothefootlengthtooexistspotentiallyinthetwo—footlength，butactuallyonlywhenithasbeenseparatedfromthewhole。Butobjectiveincrementssosmallasthoseabovemightwell，ifseparatedfromtheirtotals，[insteadofachieving’actual’exisistence]bedissolvedintheirenvironments，likeadropofsapidmoisturepouredoutintothesea。Butevenifthiswerenotso[sc。withtheobjectivemagnitude]，still，sincethe[subjective]ofsense—perceptionisnotperceptibleinitself，norcapableofseparateexistence（sinceitexistsonlypotentiallyinthemoredistinctlyperceivablewholeofsense—perception），soneitherwillitbepossibletoperceive[actually]itscorrelativelysmallobject[sc。itsquantumofpathemaorsensiblequality]whenseparatedfromtheobject—total。Butyetthis[smallobject]istobeconsideredasperceptible：foritisbothpotentiallysoalready[i。e。evenwhenalone]，anddestinedtobeactuallysowhenithasbecomepartofanaggregate。Thus，therefore，wehaveshownthatsomemagnitudesandtheirsensiblequalitiesescapenotice，andthereasonwhytheydoso，aswellasthemannerinwhichtheyarestillperceptibleornotperceptibleinsuchcases。Accordinglythenwhenthese[minutelysubdivided]
sensibleshaveonceagainbecomeaggregatedinawholeinsuchamanner，relativelytooneanother，astobeperceptibleactually，andnotmerelybecausetheyareinthewhole，butevenapartfromit，itfollowsnecessarily[fromwhathasbeenalreadystated]thattheirsensiblequalities，whethercoloursortastesorsounds，arelimitedinnumber。
Onemightask：—dotheobjectsofsense—perception，orthemovementsproceedingfromthem（[sincemovementsthereare，]inwhicheverofthetwoways[viz。byemanationsorbystimulatorykinesis]sense—perceptiontakesplace），whentheseareactualizedforperception，alwaysarrivefirstataspatialmiddlepoint[betweenthesense—organanditsobject]，asOdourevidentlydoes，andalsoSound？Forhewhoisnearer[totheodorousobject]perceivestheOdoursooner[thanwhoisfartheraway]，andtheSoundofastrokereachesussometimeafterithasbeenstruck。Isitthusalsowithanobjectseen，andwithLight？Empedocles，forexample，saysthattheLightfromtheSunarrivesfirstintheinterveningspacebeforeitcomestotheeye，orreachestheEarth。Thismightplausiblyseemtobethecase。Forwhateverismoved[inspace]，ismovedfromoneplacetoanother；hencetheremustbeacorrespondingintervaloftimealsoinwhichitismovedfromtheoneplacetotheother。Butanygiventimeisdivisibleintoparts；sothatweshouldassumeatimewhenthesun’sraywasnotasyetseen，butwasstilltravellinginthemiddlespace。
Now，evenifitbetruethattheactsof’hearing’and’havingheard’，and，generally，thoseof’perceiving’and’havingperceived’，formco—instantaneouswholes，inotherwords，thatactsofsense—perceptiondonotinvolveaprocessofbecoming，buthavetheirbeingnonethelesswithoutinvolvingsuchaprocess；yet，justas，[inthecaseofsound]，thoughthestrokewhichcausestheSoundhasbeenalreadystruck，theSoundisnotyetattheear（andthatthislastisafactisfurtherprovedbythetransformationwhichtheletters[viz。theconsonantsasheard]undergo[inthecaseofwordsspokenfromadistance]，implyingthatthelocalmovement[involvedinSound]takesplaceinthespacebetween[usandthespeaker]；forthereasonwhy[personsaddressedfromadistance]donotsucceedincatchingthesenseofwhatissaidisevidentlythattheair[soundwave]inmovingtowardsthemhasitsformchanged）
[grantingthis，then，thequestionarises]：isthesamealsotrueinthecaseofColourandLight？Forcertainlyitisnottruethatthebeholdersees，andtheobjectisseen，invirtueofsomemerelyabstractrelationshipbetweenthem，suchasthatbetweenequals。Forifitwereso，therewouldbenoneed[asthereis]thateither[thebeholderorthethingbeheld]shouldoccupysomeparticularplace；
sincetotheequalizationofthingstheirbeingnearto，orfarfrom，oneanothermakesnodifference。
Nowthis[travellingthroughsuccessivepositionsinthemedium]maywithgoodreasontakeplaceasregardsSoundandOdour，forthese，like[theirmedia]AirandWater，arecontinuous，butthemovementofbothisdividedintoparts。Thistooisthegroundofthefactthattheobjectwhichthepersonfirstinorderofproximityhearsorsmellsisthesameasthatwhicheachsubsequentpersonperceives，whileyetitisnotthesame。
Some，indeed，raiseaquestionalsoontheseverypoints；theydeclareitimpossiblethatonepersonshouldhear，orsee，orsmell，thesameobjectasanother，urgingtheimpossibilityofseveralpersonsindifferentplaceshearingorsmelling[thesameobject]，fortheonesamethingwould[thus]bedividedfromitself。Theansweristhat，inperceivingtheobjectwhichfirstsetupthemotion—e。g。
abell，orfrankincense，orfire—allperceiveanobjectnumericallyoneandthesame；while，ofcourse，inthespecialobjectperceivedtheyperceiveanobjectnumericallydifferentforeach，thoughspecificallythesameforall；andthis，accordingly，explainshowitisthatmanypersonstogethersee，orsmell，orhear[thesameobject]。Thesethings[theodourorsoundproper]arenotbodies，butanaffectionorprocessofsomekind（otherwisethis[viz。
simultaneousperceptionoftheoneobjectbymany]wouldnothavebeen，asitis，afactofexperience）though，ontheotherhand，theyeachimplyabody[astheircause]。
But[thoughsoundandodourmaytravel，]withregardtoLightthecaseisdifferent。ForLighthasitsraisond’etreinthebeing[notbecoming]ofsomething，butitisnotamovement。Andingeneral，eveninqualitativechangethecaseisdifferentfromwhatitisinlocalmovement[bothbeingdifferentspeciesofkinesis]。Localmovements，ofcourse，arrivefirstatapointmidwaybeforereachingtheirgoal（andSound，itiscurrentlybelieved，isamovementofsomethinglocallymoved），butwecannotgoontoassertthis[arrivalatapointmidway]likemannerofthingswhichundergoqualitativechange。Forthiskindofchangemayconceivablytakeplaceinathingallatonce，withoutonehalfofitbeingchangedbeforetheother；e。g。itisconceivablethatwatershouldbefrozensimultaneouslyineverypart。Butstill，forallthat，ifthebodywhichisheatedorfrozenisextensive，eachpartofitsuccessivelyisaffectedbythepartcontiguous，whilethepartfirstchangedinqualityissochangedbythecauseitselfwhichoriginatesthechange，andthusthechangethroughoutthewholeneednottakeplacecoinstantaneouslyandallatonce。Tastingwouldhavebeenassmellingnowis，ifwelivedinaliquidmedium，andperceived[thesapidobject]atadistance，beforetouchingit。
Naturally，then，thepartsofmediabetweenasensoryorgananditsobjectarenotallaffectedatonce—exceptinthecaseofLight[illumination]forthereasonabovestated，andalsointhecaseofseeing，forthesamereason；forLightisanefficientcauseofseeing。
7
Anotherquestionrespectingsense—perceptionisasfollows：
assuming，asisnatural，thatoftwo[simultaneous]sensorystimulithestrongeralwaystendstoextrudetheweaker[fromconsciousness]，isitconceivableornotthatoneshouldbeabletodiscerntwoobjectscoinstantaneouslyinthesameindividualtime？Theaboveassumptionexplainswhypersonsdonotperceivewhatisbroughtbeforetheireyes，iftheyareatthetimedeepinthought，orinafright，orlisteningtosomeloudnoise。Thisassumption，then，mustbemade，andalsothefollowing：thatitiseasiertodiscerneachobjectofsensewheninitssimpleformthanwhenaningredientinamixture；easier，forexample，todiscernwinewhenneatthanwhenblended，andsoalsohoney，and[inotherprovinces]acolour，ortodiscernthenetebyitselfalone，than[whensoundedwiththehypate]intheoctave；thereasonbeingthatcomponentelementstendtoefface[thedistinctivecharacteristicsof]oneanother。Suchistheeffect[ononeanother]ofallingredientsofwhich，whencompounded，someonethingisformed。
If，then，thegreaterstimulustendstoexpeltheless，itnecessarilyfollowsthat，whentheyconcur，thisgreatershoulditselftoobelessdistinctlyperceptiblethanifitwerealone，sincethelessbyblendingwithithasremovedsomeofitsindividuality，accordingtoourassumptionthatsimpleobjectsareinallcasesmoredistinctlyperceptible。
Now，ifthetwostimuliareequalbutheterogeneous，noperceptionofeitherwillensue；theywillalikeeffaceoneanother’scharacteristics。Butinsuchacasetheperceptionofeitherstimulusinitssimpleformisimpossible。Henceeithertherewillthenbenosense—perceptionatall，ortherewillbeaperceptioncompoundedofbothanddifferingfromeither。Thelatteriswhatactuallyseemstoresultfromingredientsblendedtogether，whatevermaybethecompoundinwhichtheyaresomixed。
Since，then，fromsomeconcurrent[sensorystimuli]aresultantobjectisproduced，whilefromothersnosuchresultantisproduced，andofthelattersortarethosethingswhichbelongtodifferentsenseprovinces（foronlythosethingsarecapableofmixturewhoseextremesarecontraries，andnoonecompoundcanbeformedfrom，e。g。WhiteandSharp，exceptindirectly，i。e。notasaconcordisformedofSharpandGrave）；therefollowslogicallytheimpossibilityofdiscerningsuchconcurrentstimulicoinstantaneously。
Forwemustsupposethatthestimuli，whenequal，tendaliketoeffaceoneanother，sincenoone[formofstimulus]resultsfromthem；while，iftheyareunequal，thestrongeraloneisdistinctlyperceptible。
Again，thesoulwouldbemorelikelytoperceivecoinstantaneously，withoneandthesamesensoryact，twothingsinthesamesensoryprovince，suchastheGraveandtheSharpinsound；
forthesensorystimulationinthisoneprovinceismorelikelytobeunitemporalthanthatinvolvingtwodifferentprovinces，asSightandHearing。Butitisimpossibletoperceivetwoobjectscoinstantaneouslyinthesamesensoryactunlesstheyhavebeenmixed，[when，however，theyarenolongertwo]，fortheiramalgamationinvolvestheirbecomingone，andthesensoryactrelatedtooneobjectisitselfone，andsuchact，whenone，is，ofcourse，coinstantaneouswithitself。Hence，whenthingsaremixedweofnecessityperceivethemcoinstantaneously：forweperceivethembyaperceptionactuallyone。Foranobjectnumericallyonemeansthatwhichisperceivedbyaperceptionactuallyone，whereasanobjectspecificallyonemeansthatwhichisperceivedbyasensoryactpotentiallyone[i。e。byanenergeiaofthesamesensuousfaculty]。Ifthentheactualizedperceptionisone，itwilldeclareitsdatatobeoneobject；theymust，therefore，havebeenmixed。Accordingly，whentheyhavenotbeenmixed，theactualizedperceptionswhichperceivethemwillbetwo；but[ifso，theirperceptionmustbesuccessivenotcoinstantaneous，for]inoneandthesamefacultytheperceptionactualizedatanysinglemomentisnecessarilyone，onlyonestimulationorexertionofasinglefacultybeingpossibleatasingleinstant，andinthecasesupposedherethefacultyisone。Itfollows，therefore，thatwecannotconceivethepossibilityofperceivingtwodistinctobjectscoinstantaneouslywithoneandthesamesense。
Butifitbethusimpossibletoperceivecoinstantaneouslytwoobjectsinthesameprovinceofsenseiftheyarereallytwo，manifestlyitisstilllessconceivablethatweshouldperceivecoinstantaneouslyobjectsintwodifferentsensoryprovinces，asWhiteandSweet。ForitappearsthatwhentheSoulpredicatesnumericalunityitdoessoinvirtueofnothingelsethansuchcoinstantaneousperception[ofoneobject，inoneinstant，byoneenergeia]：whileitpredicatesspecificunityinvirtueof[theunityof]thediscriminatingfacultyofsensetogetherwith[theunityof]themodeinwhichthisoperates。WhatImean，forexample，isthis；thesamesensenodoubtdiscernsWhiteandBlack，[whicharehencegenericallyone]thoughspecificallydifferentfromoneanother，andso，too，afacultyofsenseself—identical，butdifferentfromtheformer，discernsSweetandBitter；butwhileboththesefacultiesdifferfromoneanother[andeachfromitself]intheirmodesofdiscerningeitheroftheirrespectivecontraries，yetinperceivingtheco—ordinatesineachprovincetheyproceedinmannersanalogoustooneanother；forinstance，asTasteperceivesSweet，soSightperceivesWhite；andasthelatterperceivesBlack，sotheformerperceivesBitter。
Again，ifthestimuliofsensederivedfromContrariesarethemselvesContrary，andifContrariescannotbeconceivedassubsistingtogetherinthesameindividualsubject，andifContraries，e。g。SweetandBitter，comeunderoneandthesamesense—faculty，wemustconcludethatitisimpossibletodiscernthemcoinstantaneously。
Itislikewiseclearlyimpossiblesotodiscernsuchhomogeneoussensiblesasarenot[indeed]Contrary，[butareyetofdifferentspecies]。Fortheseare，[inthesphereofcolour，forinstance]，classedsomewithWhite，otherswithBlack，andsoitis，likewise，intheotherprovincesofsense；forexample，ofsavours，someareclassedwithSweet，andotherswithBitter。Norcanonediscernthecomponentsincompoundscoinstantaneously（fortheseareratiosofContraries，ase。g。theOctaveortheFifth）；unless，indeed，onconditionofperceivingthemasone。Forthus，andnototherwise，theratiosoftheextremesoundsarecompoundedintooneratio：
sinceweshouldhavetogethertheratio，ontheonehand，ofManytoFeworofOddtoEven，ontheother，thatofFewtoManyorofEventoOdd[andthese，tobeperceivedtogether，mustbeunified]。
If，then，thesensiblesdenominatedco—ordinatesthoughindifferentprovincesofsense（e。g。IcallSweetandWhiteco—ordinatesthoughindifferentprovinces）standyetmorealoof，anddiffermore，fromoneanotherthandoanysensiblesinthesameprovince；whileSweetdiffersfromWhiteevenmorethanBlackdoesfromWhite，itisstilllessconceivablethatoneshoulddiscernthem[viz。sensiblesindifferentsensoryprovinceswhetherco—ordinatesornot]
coinstantaneouslythansensibleswhichareinthesameprovince。
Therefore，ifcoinstantaneousperceptionofthelatterbeimpossible，thatoftheformerisafortioriimpossible。
Someofthewriterswhotreatofconcordsassertthatthesoundscombinedinthesedonotreachussimultaneously，butonlyappeartodoso，theirrealsuccessivenessbeingunnoticedwheneverthetimeitinvolvesis[sosmallastobe]imperceptible。Isthistrueornot？
Onemightperhaps，followingthisup，gosofarastosaythateventhecurrentopinionthatoneseesandhearscoinstantaneouslyisduemerelytothefactthattheintervalsoftime[betweenthereallysuccessiveperceptionsofsightandhearing]escapeobservation。Butthiscanscarcelybetrue，norisitconceivablethatanyportionoftimeshouldbe[absolutely]imperceptible，orthatanyshouldbeabsolutelyunnoticeable；thetruthbeingthatitispossibletoperceiveeveryinstantoftime。[Thisisso]；because，ifitisinconceivablethatapersonshould，whileperceivinghimselforaughtelseinacontinuoustime，beatanyinstantunawareofhisownexistence；while，obviously，theassumption，thatthereisinthetime—continuumatimesosmallastobeabsolutelyimperceptible，carriestheimplicationthatapersonwould，duringsuchtime，beunawareofhisownexistence，aswellasofhisseeingandperceiving；[thisassumptionmustbefalse]。
Again，ifthereisanymagnitude，whethertimeorthing，absolutelyimperceptibleowingtoitssmallness，itfollowsthattherewouldnotbeeitherathingwhichoneperceives，oratimeinwhichoneperceivesit，unlessinthesensethatinsomepartofthegiventimeheseessomepartofthegiventhing。For[lettherebealineab，dividedintotwopartsatg，andletthislinerepresentawholeobjectandacorrespondingwholetime。Now，]ifoneseesthewholeline，andperceivesitduringatimewhichformsoneandthesamecontinuum，onlyinthesensethathedoessoinsomeportionofthistime，letussupposethepartgb，representingatimeinwhichbysuppositionhewasperceivingnothing，cutofffromthewhole。Well，then，heperceivesinacertainpart[viz。intheremainder]ofthetime，orperceivesapart[viz。theremainder]oftheline，afterthefashioninwhichoneseesthewholeearthbyseeingsomegivenpartofit，orwalksinayearbywalkinginsomegivenpartoftheyear。But[byhypothesis]inthepartbgheperceivesnothing：
therefore，infact，heissaidtoperceivethewholeobjectandduringthewholetimesimplybecauseheperceives[somepartoftheobject]
insomepartofthetimeab。Butthesameargumentholdsalsointhecaseofag[theremainder，regardedinitsturnasawhole]；foritwillbefound[onthistheoryofvacanttimesandimperceptiblemagnitudes]thatonealwaysperceivesonlyinsomepartofagivenwholetime，andperceivesonlysomepartofawholemagnitude，andthatitisimpossibletoperceiveany[really]whole[objectinareallywholetime；aconclusionwhichisabsurd，asitwouldlogicallyannihilatetheperceptionofbothObjectsandTime]。
Thereforewemustconcludethatallmagnitudesareperceptible，buttheiractualdimensionsdonotpresentthemselvesimmediatelyintheirpresentationasobjects。Oneseesthesun，orafour—cubitrodatadistance，asamagnitude，buttheirexactdimensionsarenotgivenintheirvisualpresentation：nay，attimesanobjectofsightappearsindivisible，but[visionlikeotherspecialsenses，isfalliblerespecting’commonsensibles’，e。g。magnitude，and]nothingthatoneseesisreallyindivisible。Thereasonofthishasbeenpreviouslyexplained。Itisclearthen，fromtheabovearguments，thatnoportionoftimeisimperceptible。
Butwemustherereturntothequestionproposedabovefordiscussion，whetheritispossibleorimpossibletoperceiveseveralobjectscoinstantaneously；by’coinstantaneously’Imeanperceivingtheseveralobjectsinatimeoneandindivisiblerelativelytooneanother，i。e。indivisibleinasenseconsistentwithitsbeingallacontinuum。
First，then，isitconceivablethatoneshouldperceivethedifferentthingscoinstantaneously，buteachwithadifferentpartoftheSoul？Or[mustweobject]that，inthefirstplace，tobeginwiththeobjectsofoneandthesamesense，e。g。Sight，ifweassumeit[theSoulquaexercisingSight]toperceiveonecolourwithonepart，andanothercolourwithadifferentpart，itwillhaveapluralityofpartsthesameinspecies，[astheymustbe，]sincetheobjectswhichitthusperceivesfallwithinthesamegenus？
Shouldanyone[toillustratehowtheSoulmighthaveinittwodifferentpartsspecificallyidentical，eachdirectedtoasetofaisthetathesameingenuswiththattowhichtheotherisdirected]
urgethat，astherearetwoeyes，sotheremaybeintheSoulsomethinganalogous，[thereplyis]thatoftheeyes，doubtless，someoneorganisformed，andhencetheiractualizationinperceptionisone；butifthisissointheSoul，then，insofaraswhatisformedofboth[i。e。ofanytwospecificallyidenticalpartsasassumed]isone，thetrueperceivingsubjectalsowillbeone，[andthecontradictoryoftheabovehypothesis（ofdifferentpartsofSoulremainingengagedinsimultaneousperceptionwithonesense）iswhatemergesfromtheanalogy]；whileifthetwopartsofSoulremainseparate，theanalogyoftheeyeswillfail，[forofthesesomeoneisreallyformed]。
Furthermore，[onthesuppositionoftheneedofdifferentpartsofSoul，co—operatingineachsense，todiscerndifferentobjectscoinstantaneously]，thesenseswillbeeachatthesametimeoneandmany，asifweshouldsaythattheywereeachasetofdiversesciences；forneitherwillan’activity’existwithoutitsproperfaculty，norwithoutactivitywilltherebesensation。
ButiftheSouldoesnot，inthewaysuggested[i。e。withdifferentpartsofitselfactingsimultaneously]，perceiveinoneandthesameindividualtimesensiblesofthesamesense，afortioriitisnotthusthatitperceivessensiblesofdifferentsenses。Foritis，asalreadystated，moreconceivablethatitshouldperceiveapluralityoftheformertogetherinthiswaythanapluralityofheterogeneousobjects。
Ifthen，asisthefact，theSoulwithonepartperceivesSweet，withanother，White，eitherthatwhichresultsfromtheseissomeonepart，orelsethereisnosuchoneresultant。Buttheremustbesuchanone，inasmuchasthegeneralfacultyofsense—perceptionisone。Whatoneobject，then，doesthatonefaculty[whenperceivinganobject，e。g。asbothWhiteandSweet]perceive？[None]；forassuredlynooneobjectarisesbycompositionofthese[heterogeneousobjects，suchasWhiteandSweet]。Wemustconclude，therefore，thatthereis，ashasbeenstatedbefore，someonefacultyinthesoulwithwhichthelatterperceivesallitspercepts，thoughitperceiveseachdifferentgenusofsensiblesthroughadifferentorgan。
Maywenot，then，conceivethisfacultywhichperceivesWhiteandSweettobeonequaindivisible[sc。quacombiningitsdifferentsimultaneousobjects]initsactualization，butdifferent，whenithasbecomedivisible[sc。quadistinguishingitsdifferentsimultaneousobjects]initsactualization？
OriswhatoccursinthecaseoftheperceivingSoulconceivablyanalogoustowhatholdstrueinthatofthethingsthemselves？Forthesamenumericallyonethingiswhiteandsweet，andhasmanyotherqualities，[whileitsnumericalonenessisnottherebyprejudiced]
ifthefactisnotthatthequalitiesarereallyseparableintheobjectfromoneanother，butthatthebeingofeachqualityisdifferent[fromthatofeveryother]。Inthesamewaythereforewemustassumealso，inthecaseoftheSoul，thatthefacultyofperceptioningeneralisinitselfnumericallyoneandthesame，butdifferent[differentiated]initsbeing；different，thatistosay，ingenusasregardssomeofitsobjects，inspeciesasregardsothers。
Hencetoo，wemayconcludethatonecanperceive[numericallydifferentobjects]coinstantaneouslywithafacultywhichisnumericallyoneandthesame，butnotthesameinitsrelationship[sc。accordingastheobjectstowhichitisdirectedarenotthesame]。
Thateverysensibleobjectisamagnitude，andthatnothingwhichitispossibletoperceiveisindivisible，maybethusshown。Thedistancewhenceanobjectcouldnotbeseenisindeterminate，butthatwhenceitisvisibleisdeterminate。WemaysaythesameoftheobjectsofSmellingandHearing，andofallsensiblesnotdiscernedbyactualcontact。Now，thereis，intheintervalofdistance，someextremeplace，thelastfromwhichtheobjectisinvisible，andthefirstfromwhichitisvisible。Thisplace，beyondwhichiftheobjectbeonecannotperceiveit，whileiftheobjectbeonthehithersideonemustperceiveit，is，Ipresume，itselfnecessarilyindivisible。
Therefore，ifanysensibleobjectbeindivisible，suchobject，ifsetinthesaidextremeplacewhenceimperceptibilityendsandperceptibilitybegins，willhavetobebothvisibleandinvisibletheirobjects，whetherregardedingeneraloratthesametime；butthisisimpossible。
ThisconcludesoursurveyofthecharacteristicsoftheorgansofSense—perceptionandtheirobjects，whetherregardedingeneralorinrelationtoeachorgan。Oftheremainingsubjects，wemustfirstconsiderthatofmemoryandremembering。