In　the　Hippocratic　writings　is　summed　up　the　experience　of　Greece　to　the　Golden　Age　of　Pericles。　　Out　of　philosophy；　out　of　abstract　speculation；　had　come　a　way　of　looking　at　nature　for　which　the　physicians　were　mainly　responsible；　and　which　has　changed　forever　men's　views　on　disease。　Medicine　broke　its　leading　strings　to　religion　and　philosophya　tottering；　though　lusty；　child　whose　fortunes　we　are　to　follow　in　these　lectures。　I　have　a　feeling　that；　could　we　know　more　of　the　medical　history　of　the　older　races　of　which　I　spoke　in　the　first　lecture；　we　might　find　that　this　was　not　the　first…born　of　Asklepios；that　there　had　been　many　premature　births；　many　still…born　offspring；　even　live…births　the　products　of　the　fertilization　of　nature　by　the　human　mind；　but　the　record　is　dark；　and　the　infant　was　cast　out　like　Israel　in　the　chapter　of　Isaiah。　　But　the　high…water　mark　of　mental　achievement　had　not　been　reached　by　the　great　generation　in　which　Hippocrates　had　labored。　Socrates　had　been　dead　sixteen　years；　and　Plato　was　a　man　of　forty…five；　when　far　away　in　the　north　in　the　little　town　of　Stagira；　on　the　peninsula　of　Mount　Athos　in　Macedoniawas；　in　384　B。C。；　born　a　〃man　of　men；〃　the　one　above　all　others　to　whom　the　phrase　of　Milton　may　be　applied。　The　child　of　an　Asklepiad；　Nicomachus；　physician　to　the　father　of　Philip；　there　must　have　been　a　rare　conjunction　of　the　planets　at　the　birth　of　the　great　Stagirite。　In　the　first　circle　of　the　〃Inferno；〃　Virgil　leads　Dante　into　a　wonderful　company；　〃star…seated〃　on　the　verdure　（he　says）the　philosophic　family　looking　with　reverence　on　〃the　Master　of　those　who　know〃il　maestro　di　color　che　sanno。＇28＇　And　with　justice　has　Aristotle　been　so　regarded　for　these　twenty…three　centuries。　No　man　has　ever　swayed　such　an　intellectual　empirein　logic；　metaphysics；　rhetoric；　psychology；　ethics；　poetry；　politics　and　natural　history；　in　all　a　creator；　and　in　all　still　a　master。　The　history　of　the　human　mindoffers　no　parallel　to　his　career。　As　the　creator　of　the　sciences　of　comparative　anatomy；　systematic　zoology；　embryology；　teratology；　botany　and　physiology；　his　writings　have　an　eternal　interest。　　They　present　an　extraordinary　accumulation　of　facts　relating　to　the　structure　and　functions　of　various　parts　of　the　body。　It　is　an　unceasing　wonder　how　one　man；　even　with　a　school　of　devoted　students；　could　have　done　so　much。
  ＇28＇　The　〃Good　collector　of　qualities；〃　Dioscorides；　Hippocrates；　Avicenna；　Galen　and　Averroes　were　the　medical　members　of　the　group。　　Dante；　Inferno；　canto　iv。
  Dissectionalready　practiced　by　Alcmaeon；　Democritus；　Diogenes　and　otherswas　conducted　on　a　large　scale；　but　the　human　body　was　still　taboo。　Aristotle　confesses　that　the　〃inward　parts　of　man　are　known　least　of　all；〃　and　he　had　never　seen　the　human　kidneys　or　uterus。　　In　his　physiology；　I　can　refer　to　but　one　pointthe　pivotal　question　of　the　heart　and　blood　vessels。　To　Aristotle　the　heart　was　the　central　organ　controlling　the　circulation；　the　seat　of　vitality；　the　source　of　the　blood；　the　place　in　which　it　received　its　final　elaboration　and　impregnation　with　animal　heat。　The　blood　was　contained　in　the　heart　and　vessels　as　in　a　vasehence　the　use　of　the　term　〃vessel。〃　〃From　the　heart　the　blood…vessels　extend　throughout　the　body　as　in　the　anatomical　diagrams　which　are　represented　on　the　walls；　for　the　parts　lie　round　these　because　they　are　formed　out　of　them。〃＇29＇　The　nutriment　oozes　through　the　blood　vessels　and　the　passages　in　each　of　the　parts　〃like　water　in　unbaked　pottery。〃　He　did　not　recognize　any　distinction　between　arteries　and　veins；　calling　both　plebes　（Littre）；　the　vena　cave　is　the　great　vessel；　and　the　aorta　the　smaller；　but　both　contain　blood。　　He　did　not　use　the　word　〃arteria〃　（arthria）　for　either　of　them。　　There　was　no　movement　from　the　heart　to　the　vessels　but　the　blood　was　incessantly　drawn　upon　by　the　substance　of　the　body　and　as　unceasingly　renewed　by　absorption　of　the　products　of　digestion；the　mesenteric　vessels　taking　up　nutriment　very　much　as　the　plants　take　theirs　by　the　roots　from　the　soil。　From　the　lungs　was　absorbed　the　pneuma；　or　spiritus；　which　was　conveyed　to　the　heart　by　the　pulmonary　vesselsone　to　the　right；　and　one　to　the　left　side。　　These　vessels　in　the　lungs；　〃through　mutual　contact〃　with　the　branches　of　the　trachea；　took　in　the　pneuma。　　A　point　of　interest　is　that　the　windpipe；or　trachea；　is　called　〃arteria；〃　both　by　Aristotle　and　by　Hippocrates　（〃Anatomy；〃　Littre；　VIII；　539）。　It　was　the　air…tube；　disseminating　the　breath　through　the　lungs。　　We　shall　see　in　a　few　minutes　how　the　term　came　to　be　applied　to　the　arteries；　as　we　know　them。　The　pulsation　of　the　heart　and　arteries　was　regarded　by　Aristotle　as　a　sort　of　ebullition　in　which　the　liquids　were　inflated　by　the　vital　or　innate　heat；　the　fires　of　which　were　cooled　by　the　pneuma　taken　in　by　the　lungs　and　carried　to　the　heart　by　the　pulmonary　vessels。
  ＇29＇　De　Generatione　Animalium；　Oxford　translation；　Bk。　II；　Chap。　6；　Works　V；　743　a。
  In　Vol。　IV　of　Gomperz'　〃Greek　Thinkers；〃　you　will　find　an　admirable　discussion　on　Aristotle　as　an　investigator　of　nature；　and　those　of　you　who　wish　to　study　his　natural　history　works　more　closely　may　do　so　easilyin　the　new　translation　which　is　in　process　of　publication　by　the　Clarendon　Press；　Oxford。　　At　the　end　of　the　chapter　〃De　Respiratione〃in　the　〃Parva　Naturalia〃　（Oxford　edition；　1908）；　we　have　Aristotle's　attitude　towards　medicine　expressed　in　a　way　worthy　of　a　son　of　the　profession：
  〃But　health　and　disease　also　claim　the　attention　of　the　scientist；　and　not　merely　of　the　physician；　in　so　far　as　an　account　of　their　causes　is　concerned。　The　extent　to　which　these　two　differ　and　investigate　diverse　provinces　must　not　escape　us；　since　facts　show　that　their　inquiries　are；　at　least　to　a　certain　extent；　conterminous。　　For　physicians　of　culture　and　refinement　make　some　mention　of　natural　science；and　claim　to　derive　their　principles　from　it；　while　the　most　accomplished　investigators　into　nature　generally　push　their　studies　so　far　as　to　conclude　with　an　account　of　medical　principles。〃　　（Works；　III；480　b。）
  Theophrastus；　a　student　of　Aristotle　and　his　successor；　created　the　science　of　botany　and　made　possible　the　pharmacologists　of　a　few　centuries　later。　Some　of　you　doubtless　know　him　in　another　guiseas　the　author　of　the　golden　booklet　on　〃Characters；〃　in　which　〃the　most　eminent　botanist　of　antiquity　observes　the　doings　of　men　with　the　keen　and　unerring　vision　of　a　natural　historian〃　（Gomperz）。　In　the　Hippocratic　writings；　there　are　mentioned　236　plants；　in　the　botany　of　Theophrastus；　455。　To　one　trait　of　master　and　pupil　I　must　referthe　human　feeling；　not　alone　of　man　for　man；　but　a　sympathy　that　even　claims　kinship　with　the　animal　world。　　〃The　spirit　with　which　he　（Theophrastus）　regarded　the　animal　world　found　no　second　expression　till　the　present　age〃　（Gomperz）。　Halliday；　however；makes　the　statement　that　Porphyry＇30＇　goes　as　far　as　any　modern　humanitarian　in　preaching　our　duty　towards　animals。
  ＇30＇　W。　R。　Halliday：　　Greek　Divination；　London；　Macmillan　&　Co。；　1913。
  ALEXANDRIAN　SCHOOL
  FROM　the　death　of　Hippocrates　about　the　year　375　B。C。　till　the　founding　of　the　Alexandrian　School；　the　physicians　were　engrossed　largely　in　speculative　views；　and　not　much　real　progress　was　made；　except　in　the　matter　of　elaborating　the　humoral　pathology。　Only　three　or　four　men　of　the　first　rank　stand　out　in　this　period：　Diocles　the　Carystian；　〃both　in　time　and　reputation　next　and　second　to　Hippocrates〃　（Pliny）；　a　keen　anatomist　and　an　encyclopaedic　writer；　but　only　scanty　fragments　of　his　work　remain。　　In　some　ways　the　most　important　member　of　this　group　was　Praxagoras；　a　native　of　Cos；　about　340　B。C。　Aristotle；　you　remember；　made　no　essential　distinction　between　arteries　and　veins；　both　of　which　he　held　to　contain　blood：　Praxagoras　recognized　that　the　pulsation　was　only　in　the　arteries；　and　maintained　that　only　the　veins　contained　blood；　and　the　arteries　air。　As　a　rule　the　arteries　are　empty　after　death；　and　Praxagoras　believed　that　they　were　filled　with　an　aeriform　fluid；　a　sort　of　pneuma；　which　was　responsible　for　their　pulsation。　The　word　arteria；　which　had　already　been　applied　to　the　trachea；　as　an　air…containing　tube；　was　then　attached　to　the　arteries；　on　account　of　the　rough　and　uneven　character　of　its　walls　the　trachea　was　then　called　the　arteria　tracheia；　or　the　rough　air…tube。＇31a＇　We　call　it　simply　the　trachea；　but　in　French　the　word　trachee…artere　is　still　used。
  ＇31a＇　Galen：　　De　usu　partium；　VII；　Chaps。　8…9。
  Praxagoras　was　one　of　the　first　to　make　an　exhaustive　study　of　the　pulse；　and　he　must　have　been　a　man　of　considerable　clinical　acumen；as　well　as　boldness；　to　recommend　in　obstruction　of　the　bowels　the　opening　of　the　abdomen；　removal　of　the　obstructed　portion　and　uniting　the　ends　of　the　intestine　by　sutures。
  After　the　death　of　Alexander；　Egypt　fell　into　the　hands　of　his　famous　general；　Ptolemy；　under　whose　care　the　city　became　one　of　the　most　important　on　the　Mediterranean。　　He　founded　and　maintained　a　museum；　an　establishment　that　corresponded　very　much　to　a　modern　university；　for　the　study　of　literature；　science　and　the　arts。　　Under　his　successors；　particularly　the　third　Ptolemy；　the　museum　develop