第1章

byAristotletranslatedbyG。R。T。Ross1 WEmustnowtreatofyouthandoldageandlifeanddeath。Wemustprobablyalsoatthesametimestatethecausesofrespirationaswell，sinceinsomecaseslivingandthereversedependonthis。 Wehaveelsewheregivenapreciseaccountofthesoul，andwhileitisclearthatitsessentialrealitycannotbecorporeal，yetmanifestlyitmustexistinsomebodilypartwhichmustbeoneofthosepossessingcontroloverthemembers。Letusforthepresentsetasidetheotherdivisionsorfacultiesofthesoul（whicheverofthetwobethecorrectname）。Butastobeingwhatiscalledananimalandalivingthing，wefindthatinallbeingsendowedwithbothcharacteristics（viz。beingananimalandbeingalive）theremustbeasingleidenticalpartinvirtueofwhichtheyliveandarecalledanimals；forananimalquaanimalcannotavoidbeingalive。Butathingneednot，thoughalive，beanimal，forplantslivewithouthavingsensation，anditisbysensationthatwedistinguishanimalfromwhatisnotanimal。 Thisorgan，then，mustbenumericallyoneandthesameandyetpossessmultipleanddisparateaspects，forbeinganimalandlivingarenotidentical。Sincethentheorgansofspecialsensationhaveonecommonorganinwhichthesenseswhenfunctioningmustmeet，andthismustbesituatedmidwaybetweenwhatiscalledbeforeandbehind（wecall’before’thedirectionfromwhichsensationcomes，’behind’theopposite），further，sinceinalllivingthingsthebodyisdividedintoupperandlower（theyallhaveupperandlowerparts，sothatthisistrueofplantsaswell），clearlythenutritiveprinciplemustbesituatedmidwaybetweentheseregions。 Thatpartwherefoodenterswecallupper，consideringitbyitselfandnotrelativelytothesurroundinguniverse，whiledownwardisthatpartbywhichtheprimaryexcrementisdischarged。 Plantsarethereverseofanimalsinthisrespect。Tomaninparticularamongtheanimals，onaccountofhiserectstature，belongsthecharacteristicofhavinghisupperpartspointingupwardsinthesenseinwhichthatappliestotheuniverse，whileintheotherstheseareinanintermediateposition。Butinplants，owingtotheirbeingstationaryanddrawingtheirsustenancefromtheground，theupperpartmustalwaysbedown；forthereisacorrespondencebetweentherootsinaplantandwhatiscalledthemouthinanimals，bymeansofwhichtheytakeintheirfood，whetherthesourceofsupplybetheearthoreachother’sbodies。 2 Allperfectlyformedanimalsaretobedividedintothreeparts，onethatbywhichfoodistakenin，onethatbywhichexcrementisdischarged，andthethirdtheregionintermediatebetweenthem。Inthelargestanimalsthislatteriscalledthechestandintheotherssomethingcorresponding；insomealsoitismoredistinctlymarkedoffthaninothers。Allthosealsothatarecapableofprogressionhaveadditionalmemberssubservienttothispurpose，bymeansofwhichtheybearthewholetrunk，towitlegsandfeetandwhateverpartsarepossessedofthesamepowers。Nowitisevidentbothbyobservationandbyinferencethatthesourceofthenutritivesoulisinthemidstofthethreeparts。Formanyanimals，wheneitherpart—theheadorthereceptacleofthefood—iscutoff，retainlifeinthatmembertowhichthemiddleremainsattached。Thiscanbeseentooccurinmanyinsects，e。g。waspsandbees，andmanyanimalsalsobesidesinsectscan，thoughdivided，continuetolivebymeansofthepartconnectedwithnutrition。 Whilethismemberisindeedinactualitysingle，yetpotentiallyitismultiple，fortheseanimalshaveaconstitutionsimilartothatofPlants；plantswhencutintosectionscontinuetolive，andanumberoftreescanbederivedfromonesinglesource。Aseparateaccountwillbegivenofthereasonwhysomeplantscannotlivewhendivided，whileotherscanbepropagatedbythetakingofslips。Inthisrespect，however，plantsandinsectsarealike。 Itistruethatthenutritivesoul，inbeingspossessingit，whileactuallysinglemustbepotentiallyplural。Anditistoowiththeprincipleofsensation，forevidentlythedividedsegmentsoftheseanimalshavesensation。Theyareunable，however，topreservetheirconstitution，asplantscan，notpossessingtheorgansonwhichthecontinuanceoflifedepends，forsomelackthemeansforseizing，othersforreceivingtheirfood；oragaintheymaybedestituteofotherorgansaswell。 Divisibleanimalsarelikeanumberofanimalsgrowntogether，butanimalsofsuperiorconstructionbehavedifferentlybecausetheirconstitutionisaunityofthehighestpossiblekind。Hencesomeoftheorgansondivisiondisplayslightsensitivenessbecausetheyretainsomepsychicalsusceptibility；theanimalscontinuetomoveafterthevitalshavebeenabstracted：tortoises，forexample，dosoevenafterthehearthasbeenremoved。 3 Thesamephenomenonisevidentbothinplantsandinanimals，andinplantswenoteitbothintheirpropagationbyseedandingraftsandcuttings。Genesisfromseedsalwaysstartsfromthemiddle。Allseedsarebivalvular，andtheplaceofjunctionissituatedatthepointofattachment（totheplant），anintermediatepartbelongingtobothhalves。Itisfromthispartthatbothrootandstemofgrowingthingsemerge；thestarting—pointisinacentralpositionbetweenthem。Inthecaseofgraftsandcuttingsthisisparticularlytrueofthebuds；forthebudisinawaythestarting—pointofthebranch，butatthesametimeitisinacentralposition。Henceitiseitherthisthatiscutoff，orintothisthatthenewshootisinserted，whenwewisheitheranewbranchoranewroottospringfromit；whichprovesthatthepointoforiginingrowthisintermediatebetweenstemandroot。 Likewiseinsanguineousanimalstheheartisthefirstorgandeveloped；thisisevidentfromwhathasbeenobservedinthosecaseswhereobservationoftheirgrowthispossible。Henceinbloodlessanimalsalsowhatcorrespondstotheheartmustdevelopfirst。WehavealreadyassertedinourtreatiseonThePartsofAnimalsthatitisfromtheheartthattheveinsissue，andthatinsanguineousanimalsthebloodisthefinalnutrimentfromwhichthemembersareformed。Henceitisclearthatthereisonefunctioninnutritionwhichthemouthhasthefacultyofperforming，andadifferentoneappertainingtothestomach。Butitistheheartthathassupremecontrol，exercisinganadditionalandcompletingfunction。 Henceinsanguineousanimalsthesourcebothofthesensitiveandofthenutritivesoulmustbeintheheart，forthefunctionsrelativetonutritionexercisedbytheotherpartsareancillarytotheactivityoftheheart。Itisthepartofthedominatingorgantoachievethefinalresult，asofthephysician’seffortstobedirectedtowardshealth，andnottobeoccupiedwithsubordinateoffices。 Certainly，however，allsaguineousanimalshavethesupremeorganofthesensefacultiesintheheart，foritisherethatwemustlookforthecommonsensoriumbelongingtoallthesense—organs。Theseintwocases，tasteandtouch，canbeclearlyseentoextendtotheheart，andhencetheothersalsomustleadtoit，forinittheotherorgansmaypossiblyinitiatechanges，whereaswiththeupperregionofthebodytasteandtouchhavenoconnexion。Apartfromtheseconsiderations，ifthelifeisalwayslocatedinthispart，evidentlytheprincipleofsensationmustbesituatedtheretoo，foritisquaanimalthatananimalissaidtobealivingthing，anditiscalledanimalbecauseendowedwithsensation。Elsewhereinotherworkswehavestatedthereasonswhysomeofthesense—organsare，asisevident，connectedwiththeheart，whileothersaresituatedinthehead。（Itisthisfactthatcausessomepeopletothinkthatitisinvirtueofthebrainthatthefunctionofperceptionbelongstoanimals。） 4 Thusif，ontheonehand，welooktotheobservedfacts，whatwehavesaidmakesitclearthatthesourceofthesensitivesoul，togetherwiththatconnectedwithgrowthandnutrition，issituatedinthisorganandinthecentraloneofthethreedivisionsofthebody。Butitfollowsbydeductionalso；forweseethatineverycase，whenseveralresultsareopentoher，Naturealwaysbringstopassthebest。Nowifbothprinciplesarelocatedinthemidstofthesubstance，thetwopartsofthebody，viz。thatwhichelaboratesandthatwhichreceivesthenutrimentinitsfinalformwillbestperformtheirappropriatefunction；forthesoulwillthenbeclosetoeach，andthecentralsituationwhichitwill，assuch，occupyisthepositionofadominatingpower。 Further，thatwhichemploysaninstrumentandtheinstrumentitemploysmustbedistinct（andmustbespatiallydiversetoo，ifpossible，asincapacity），justasthefluteandthatwhichplaysit—thehand—arediverse。Thusifanimalisdefinedbythepossessionofsensitivesoul，thissoulmustinthesanguineousanimalsbeintheheart，and，inthebloodlessones，inthecorrespondingpartoftheirbody。Butinanimalsallthemembersandthewholebodypossesssomeconnatewarmthofconstitution，andhencewhenalivetheyareobservedtobewarm，butwhendeadanddeprivedoflifetheyaretheopposite。Indeed，thesourceofthiswarmthmustbeintheheartinsanguineousanimals，andinthecaseofbloodlessanimalsinthecorrespondingorgan，for，thoughallpartsofthebodybymeansoftheirnaturalheatelaborateandconcoctthenutriment，thegoverningorgantakesthechiefshareinthisprocess。Hence，thoughtheothermembersbecomecold，liferemains；butwhenthewarmthhereisquenched，deathalwaysensues，becausethesourceofheatinalltheothermembersdependsonthis，andthesoulis，asitwere，setaglowwithfireinthispart，whichinsanguineousanimalsistheheartandinthebloodlessordertheanalogousmember。Hence，ofnecessity，lifemustbecoincidentwiththemaintenanceofheat，andwhatwecalldeathisitsdestruction。 5 However，itistobenoticedthattherearetwowaysinwhichfireceasestoexist；itmaygoouteitherbyexhaustionorbyextinction。Thatwhichisself—causedwecallexhaustion，thatduetoitsoppositesextinction。[Theformeristhatduetooldage，thelattertoviolence。]Buteitherofthesewaysinwhichfireceasestobemaybebroughtaboutbythesamecause，for，whenthereisadeficiencyofnutrimentandthewarmthcanobtainnomaintenance，thefirefails；andthereasonisthattheopposite，checkingdigestion，preventsthefirefrombeingfed。Butinothercasestheresultisexhaustion，—whentheheataccumulatesexcessivelyowingtolackofrespirationandofrefrigeration。Forinthiscasewhathappensisthattheheat，accumulatingingreatquantity，quicklyusesupitsnutrimentandconsumesitallbeforemoreissentupbyevaporation。Hencenotonlyisasmallerfirereadilyputoutbyalargeone，butofitselfthecandleflameisconsumedwheninsertedinalargeblazejustasisthecasewithanyothercombustible。Thereasonisthatthenutrimentintheflameisseizedbythelargeronebeforefreshfuelcanbeadded，forfireisevercomingintobeingandrushingjustlikeariver，butsospeedilyastoeludeobservation。 Clearlytherefore，ifthebodilyheatmustbeconserved（asisnecessaryiflifeistocontinue），theremustbesomewayofcoolingtheheatresidentinthesourceofwarmth。Takeasanillustrationwhatoccurswhencoalsareconfinedinabrazier。Iftheyarekeptcoveredupcontinuouslybytheso—called’choker’，theyarequicklyextinguished，but，ifthelidisinrapidalternationliftedupandputonagaintheyremainglowingforalongtime。Bankingupafirealsokeepsitin，fortheashes，beingporous，donotpreventthepassageofair，andagaintheyenableittoresistextinctionbythesurroundingairbymeansofthesupplyofheatwhichitpossesses。 However，wehavestatedinTheProblemsthereasonswhytheseoperations，namelybankingupandcoveringupafire，havetheoppositeeffects（intheonecasethefiregoesout，intheotheritcontinuesaliveforaconsiderabletime）。 6 Everythinglivinghassoul，andit，aswehavesaid，cannotexistwithoutthepresenceofheatintheconstitution。Inplantsthenaturalheatissufficientlywellkeptalivebytheaidwhichtheirnutrimentandthesurroundingairsupply。Forthefoodhasacoolingeffect[asitenters，justasithasinman]whenfirstitistakenin，whereasabstinencefromfoodproducesheatandthirst。Theair，ifitbemotionless，becomeshot，butbytheentryoffoodamotionissetupwhichlastsuntildigestioniscompletedandsocoolsit。Ifthesurroundingairisexcessivelycoldowingtothetimeofyear，therebeingseverefrost，plantsshrivel，orif，intheextremeheatsofsummerthemoisturedrawnfromthegroundcannotproduceitscoolingeffect，theheatcomestoanendbyexhaustion。Treessufferingatsuchseasonsaresaidtobeblightedorstar—stricken。 Hencethepracticeoflayingbeneaththerootsstonesofcertainspeciesorwaterinpots，forthepurposeofcoolingtherootsoftheplants。 Someanimalspasstheirlifeinthewater，othersintheair，andthereforethesemediafurnishthesourceandmeansofrefrigeration，waterintheonecase，airintheother。Wemustproceed—anditwillrequirefurtherapplicationonourpart—togiveanaccountofthewayandmannerinwhichthisrefrigerationoccurs。 7 Afewofthepreviousphysicalphilosophershavespokenofrespiration。Thereason，however，whyitexistsinanimalstheyhaveeithernotdeclaredor，whentheyhave，theirstatementsarenotcorrectandshowacomparativelackofacquaintancewiththefacts。 Moreovertheyassertthatallanimalsrespire—whichisuntrue。Hencethesepointsmustfirstclaimourattention，inorderthatwemaynotbethoughttomakeunsubstantiatedchargesagainstauthorsnolongeralive。 Firstthen，itisevidentthatallanimalswithlungsbreathe，butinsomecasesbreathinganimalshaveabloodlessandspongylung，andthenthereislessneedforrespiration。Theseanimalscanremainunderwaterforatime，whichrelativelytotheirbodilystrength，isconsiderable。Alloviparousanimals，e。g。thefrog—tribe，haveaspongylung。Alsohemydesandtortoisescanremainforalongtimeimmersedinwater；fortheirlung，containinglittleblood，hasnotmuchheat。Hence，whenonceitisinflated，ititself，bymeansofitsmotion，producesacoolingeffectandenablestheanimaltoremainimmersedforalongtime。Suffocation，however，alwaysensuesiftheanimalisforcedtoholditsbreathfortoolongatime，fornoneofthisclasstakeinwaterinthewayfishesdo。Ontheotherhand，animalswhichhavethelungchargedwithbloodhavegreaterneedofrespirationonaccountoftheamountoftheirheat，whilenoneatalloftheotherswhichdonotpossesslungsbreathe。 8 DemocritusofAbderaandcertainotherswhohavetreatedofrespiration，whilesayingnothingdefiniteaboutthelunglessanimals，neverthelessseemtospeakasifallbreathed。ButAnaxagorasandDiogenesbothmaintainthatallbreathe，andstatethemannerinwhichfishesandoystersrespire。Anaxagorassaysthatwhenfishesdischargewaterthroughtheirgills，airisformedinthemouth，fortherecanbenovacuum，andthatitisbydrawinginthisthattheyrespire。 Diogenes’statementisthat，whentheydischargewaterthroughtheirgills，theysucktheairoutofthewatersurroundingthemouthbymeansofthevacuumformedinthemouth，forhebelievesthereisairinthewater。 Butthesetheoriesareuntenable。Firstly，theystateonlywhatisthecommonelementinbothoperationsandsoleaveoutthehalfofthematter。Forwhatgoesbythenameofrespirationconsists，ontheonehand，ofinhalation，and，ontheother，oftheexhalationofbreath；but，aboutthelattertheysaynothing，nordotheydescribehowsuchanimalsemittheirbreath。Indeed，explanationisforthemimpossiblefor，whenthecreaturesrespire，theymustdischargetheirbreathbythesamepassageasthatbywhichtheydrawitin，andthismusthappeninalternation。Hence，asaresult，theymusttakethewaterintotheirmouthatthesametimeastheybreatheout。Buttheairandthewatermustmeetandobstructeachother。Further，whentheydischargethewatertheymustemittheirbreathbythemouthorthegills，andtheresultwillbethattheywillbreatheinandbreatheoutatthesametime，foritisatthatmomentthatrespirationissaidtooccur。Butitisimpossiblethattheyshoulddobothatthesametime。Hence，ifrespiringcreaturesmustbothexhaleandinhaletheair，andifnoneoftheseanimalscanbreatheout，evidentlynonecanrespireatall。 9 Further，theassertionthattheydrawinairoutofthemouthoroutofthewaterbymeansofthemouthisanimpossibility，for，nothavingalung，theyhavenowindpipe；ratherthestomachiscloselyjuxtaposedtothemouth，sothattheymustdothesuckingwiththestomach。Butinthatcasetheotheranimalswoulddosoalso，whichisnotthetruth；andthewater—animalsalsowouldbeseentodoitwhenoutofthewater，whereasquiteevidentlytheydonot。Further，inallanimalsthatrespireanddrawbreaththereistobeobservedacertainmotioninthepartofthebodywhichdrawsintheair，butinthefishesthisdoesnotoccur。Fishesdonotappeartomoveanyofthepartsintheregionofthestomach，exceptthegillsalone，andthesemovebothwhentheyareinthewaterandwhentheyarethrownontodrylandandgasp。Moreover，alwayswhenrespiringanimalsarekilledbybeingsuffocatedinwater，bubblesareformedoftheairwhichisforciblydischarged，ashappens，e。g。whenoneforcesatortoiseorafrogoranyotheranimalofasimilarclasstostaybeneathwater。Butwithfishesthisresultneveroccurs，inwhatsoeverwaywetrytoobtainit，sincetheydonotcontainairdrawnfromanexternalsource。Again，themannerofrespirationsaidtoexistinthemmightoccurinthecaseofmenalsowhentheyareunderwater。 Foriffishesdrawinairoutofthesurroundingwaterbymeansoftheirmouthwhyshouldnotmentooandotheranimalsdosoalso； theyshouldalso，inthesamewayasfishes，drawinairoutofthemouth。Ifintheformercaseitwerepossible，soalsoshoulditbeinthelatter。But，sinceintheoneitisnotso，neitherdoesitoccurintheother。Furthermore，whydofishes，iftheyrespire，dieintheairandgasp（ascanbeseen）asinsuffocation？Itisnotwantoffoodthatproducesthiseffectuponthem，andthereasongivenbyDiogenesisfoolish，forhesaysthatinairtheytakeintoomuchairandhencedie，butinthewatertheytakeinamoderateamount。Butthatshouldbeapossibleoccurrencewithlandanimalsalso；asfactsare，however，nolandanimalseemstobesuffocatedbyexcessiverespiration。Again，ifallanimalsbreathe，insectsmustdosoalso。 manyofthemseemtolivethoughdividednotmerelyintotwo，butintoseveralparts，e。g。theclasscalledScolopendra。Buthowcanthey，whenthusdivided，breathe，andwhatistheorgantheyemploy？Themainreasonwhythesewritershavenotgivenagoodaccountofthesefactsisthattheyhavenoacquaintancewiththeinternalorgans，andthattheydidnotacceptthedoctrinethatthereisafinalcauseforwhateverNaturedoes。Iftheyhadaskedforwhatpurposerespirationexistsinanimals，andhadconsideredthiswithreferencetotheorgans，e。g。thegillsandthelungs，theywouldhavediscoveredthereasonmorespeedily。 10 Democritus，however，doesteachthatinthebreathinganimalsthereisacertainresultproducedbyrespiration；heassertsthatitpreventsthesoulfrombeingextrudedfromthebody。 Nevertheless，hebynomeansassertsthatitisforthispurposethatNaturesocontrivesit，forhe，liketheotherphysicalphilosophers，altogetherfailstoattaintoanysuchexplanation。 Hisstatementisthatthesoulandthehotelementareidentical，beingtheprimaryformsamongthesphericalparticles。Hence，whenthesearebeingcrushedtogetherbythesurroundingatmospherethrustingthemout，respiration，accordingtohisaccount，comesintosuccourthem。Forintheairtherearemanyofthoseparticleswhichhecallsmindandsoul。Hence，whenwebreatheandtheairenters，theseenteralongwithit，andbytheiractioncancelthepressure，thuspreventingtheexpulsionofthesoulwhichresidesintheanimal。 Thisexplainswhylifeanddeathareboundupwiththetakinginandlettingoutofthebreath；fordeathoccurswhenthecompressionbythesurroundingairgainstheupperhand，and，theanimalbeingunabletorespire，theairfromoutsidecannolongerenterandcounteractthecompression。Deathisthedepartureofthoseformsowingtotheexpulsivepressureexertedbythesurroundingair。Death，however，occursnotbyhaphazardbut，whennatural，owingtooldage，and，whenunnatural，toviolence。 ButthereasonforthisandwhyallmustdieDemocritushasbynomeansmadeclear。Andyet，sinceevidentlydeathoccursatonetimeoflifeandnotatanother，heshouldhavesaidwhetherthecauseisexternalorinternal。Neitherdoesheassignthecauseofthebeginningofrespiration，norsaywhetheritisinternalorexternal。Indeed，itisnotthecasethattheexternalmindsuperintendsthereinforcement；rathertheoriginofbreathingandoftherespiratorymotionmustbewithin：itisnotduetopressurefromaround。Itisabsurdalsothatwhatsurroundsshouldcompressandatthesametimebyenteringdilate。Thisthenispracticallyhistheory，andhowheputsit。 Butifwemustconsiderthatourpreviousaccountistrue，andthatrespirationdoesnotoccurineveryanimal，wemustdeemthatthisexplainsdeathnotuniversally，butonlyinrespiringanimals。 Yetneitherisitagoodaccountoftheseeven，asmayclearlybeseenfromthefactsandphenomenaofwhichweallhaveexperience。Forinhotweatherwegrowwarmer，and，havingmoreneedofrespiration，wealwaysbreathefaster。But，whentheairaroundiscoldandcontractsandsolidifiesthebody，retardationofthebreathingresults。Yetthiswasjustthetimewhentheexternalairshouldenterandannultheexpulsivemovement，whereasitistheoppositethatoccurs。Forwhenthebreathisnotletoutandtheheataccumulatestoomuchthenweneedtorespire，andtorespirewemustdrawinthebreath。Whenhot，peoplebreatherapidly，becausetheymustdosoinordertocoolthemselves，justwhenthetheoryofDemocrituswouldmakethemaddfiretofire。 11 ThetheoryfoundintheTimaeus，ofthepassingroundofthebreathbypushing，bynomeansdetermineshow，inthecaseoftheanimalsotherthanland—animals，theirheatispreserved，andwhetheritisduetothesameoradifferentcause。Forifrespirationoccursonlyinland—animalsweshouldbetoldwhatisthereasonofthat。Likewise，ifitisfoundinothersalso，butinadifferentform，thisformofrespiration，iftheyallcanbreathe，mustalsobedescribed。 Further，themethodofexplaininginvolvesafiction。Itissaidthatwhenthehotairissuesfromthemouthitpushesthesurroundingair，whichbeingcarriedonenterstheveryplacewhencetheinternalwarmthissued，throughtheintersticesoftheporousflesh；andthisreciprocalreplacementisduetothefactthatavacuumcannotexist。Butwhenithasbecomehottheairpassesoutagainbythesameroute，andpushesbackinwardsthroughthemouththeairthathadbeendischargedinawarmcondition。Itissaidthatitisthisactionwhichgoesoncontinuouslywhenthebreathistakeninandletout。 Butaccordingtothiswayofthinkingitwillfollowthatwebreatheoutbeforewebreathein。Buttheoppositeisthecase，asevidenceshows，forthoughthesetwofunctionsgooninalternation，yetthelastactwhenlifecomestoacloseisthelettingoutofthebreath，andhenceitsadmissionmusthavebeenthebeginningoftheprocess。 Oncemore，thosewhogivethiskindofexplanationbynomeansstatethefinalcauseofthepresenceinanimalsofthisfunction（towittheadmissionandemissionofthebreath），buttreatitasthoughitwereacontingentaccompanimentoflife。Yetitevidentlyhascontroloverlifeanddeath，foritresultssynchronouslythatwhenrespiringanimalsareunabletobreathetheyperish。Again，itisabsurdthatthepassageofthehotairoutthroughthemouthandbackagainshouldbequiteperceptible，whilewewerenotabletodetectthethoracicinfluxandthereturnoutwardsoncemoreoftheheatedbreath。Itisalsononsensethatrespirationshouldconsistintheentranceofheat，fortheevidenceistothecontraryeffect； whatisbreathedoutishot，andwhatisbreathediniscold。Whenitishotwepantinbreathing，for，becausewhatentersdoesnotadequatelyperformitscoolingfunction，wehaveasaconsequencetodrawthebreathfrequently。 12 Itiscertain，however，thatwemustnotentertainthenotionthatitisforpurposesofnutritionthatrespirationisdesigned，andbelievethattheinternalfireisfedbythebreath；respiration，asitwere，addingfueltothefire，whilethefeedingoftheflameresultsintheoutwardpassageofthebreath。TocombatthisdoctrineIshallrepeatwhatIsaidinoppositiontotheprevioustheories。This，orsomethinganalogoustoit，shouldoccurintheotheranimalsalso（onthistheory），forallpossessvitalheat。 Further，howarewetodescribethisfictitiousprocessofthegenerationofheatfromthebreath？Observationshowsratherthatitisaproductofthefood。Aconsequencealsoofthistheoryisthatthenutrimentwouldenterandtherefusebedischargedbythesamechannel，butthisdoesnotappeartooccurintheotherinstances。 13 Empedoclesalsogivesanaccountofrespirationwithout，however，makingclearwhatitspurposeis，orwhetherornotitisuniversalinanimals。Alsowhendealingwithrespirationbymeansofthenostrilsheimaginesheisdealingwithwhatistheprimarykindofrespiration。Eventhebreathwhichpassesthroughthenostrilspassesthroughthewindpipeoutofthechestaswell，andwithoutthelatterthenostrilscannotact。Again，whenanimalsarebereftofrespirationthroughthenostrils，nodetrimentalresultensues，but，whenpreventedfrombreathingthroughthewindpipe，theydie。 Natureemploysrespirationthroughthenostrilsasasecondaryfunctionincertainanimalsinordertoenablethemtosmell。Butthereasonwhyitexistsinsomeonlyisthatthoughalmostallanimalsareendowedwiththesenseofsmell，thesense—organisnotthesameinall。 Amorepreciseaccounthasbeengivenaboutthiselsewhere。 Empedocles，however，explainsthepassageinwardsandoutwardsofthebreath，bythetheorythattherearecertainblood—vessels，which，whilecontainingblood，arenotfilledbyit，buthavepassagesleadingtotheouterair，thecalibreofwhichisfineincontrasttothesizeofthesolidparticles，butlargerelativelytothoseintheair。Hence，sinceitisthenatureofthebloodtomoveupwardsanddownwards，whenitmovesdowntheairrushesinandinspirationoccurs；whenthebloodrises，theairisforcedoutandtheoutwardmotionofthebreathresults。Hecomparesthisprocesstowhatoccursinaclepsydra。 Thusallthingsoutwardsbreatheandin；—theirfleshhastubesBloodless，thatstretchtowardsthebody’soutmostedge，Which，attheirmouths，fullmanyfrequentchannelspierce，Cleavingtheextremenostrilsthrough；thus，whilethegoreLieshid，forairiscutathoroughfaremostplain。 Andthence，whenevershrinksawaythetenderblood，Enterstheblusteringwindwithswellingbillowwild。 Butwhenthebloodleapsup，backwarditbreathes。AswhenWithwater—clockofpolishedbronzeamaidensporting，SetsonhercomelyhandthenarrowofthetubeAnddipsitinthefrail—formedwater’ssilverysheen； Notthenthefloodthevesselenters，buttheair，Untilshefreesthecrowdedstream。ButthenindeedUpontheescaperunsinthewatermeet。 Soalsowhenwithinthevessel’sdeepsthewaterRemains，theopeningbythehandoffleshbeingclosed，TheouterairthatentrancecravesrestrainsthefloodAtthegatesofthesoundingnarrow，uponthesurfacepressing，Untilthemaidwithdrawsherhand。ButthenincontrariwiseOncemoretheaircomesinandwatermeetflowsout。 Thustothetothesubtleblood，surgingthroughoutthelimbs，Whene’eritshrinksawayintothefarrecessesAdmitsastreamofairrushingwithswellingwave，But，whenitbackwardleaps，inlikebulkairflowsout。