a history of science-1-第3章

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elegated　such　objects　as　trees　to　the　ranks　of　the　non…living；　but　that　he　recognized　a　fundamental　distinction　between；　let　us　say；　a　wolf　and　a　granite　bowlder　we　cannot　well　doubt。　A　step　beyond　thisa　step；　however；　that　may　have　required　centuries　or　millenniums　in　the　takingmust　have　carried　man　to　a　plane　of　intelligence　from　which　a　primitive　Aristotle　or　Linnaeus　was　enabled　to　note　differences　and　resemblances　connoting　such　groups　of　things　as　fishes；　birds；　and　furry　beasts。　This　conception；　to　be　sure；　is　an　abstraction　of　a　relatively　high　order。　We　know　that　there　are　savage　races　to…day　whose　language　contains　no　word　for　such　an　abstraction　as　bird　or　tree。　We　are　bound　to　believe；　then；　that　there　were　long　ages　of　human　progress　during　which　the　highest　man　had　attained　no　such　stage　of　abstraction；　but；　on　the　other　hand；　it　is　equally　little　in　question　that　this　degree　of　mental　development　had　been　attained　long　before　the　opening　of　our　historical　period。　The　primeval　man；　then；　whose　scientific　knowledge　we　are　attempting　to　predicate；　had　become；　through　his　conception　of　fishes；　birds；　and　hairy　animals　as　separate　classes；　a　scientific　zoologist　of　relatively　high　attainments。　In　the　practical　field　of　medical　knowledge；　a　certain　stage　of　development　must　have　been　reached　at　a　very　early　day。　Even　animals　pick　and　choose　among　the　vegetables　about　them；　and　at　times　seek　out　certain　herbs　quite　different　from　their　ordinary　food；　practising　a　sort　of　instinctive　therapeutics。　The　cat's　fondness　for　catnip　is　a　case　in　point。　The　most　primitive　man；　then；　must　have　inherited　a　racial　or　instinctive　knowledge　of　the　medicinal　effects　of　certain　herbs；　in　particular　he　must　have　had　such　elementary　knowledge　of　toxicology　as　would　enable　him　to　avoid　eating　certain　poisonous　berries。　Perhaps；　indeed；　we　are　placing　the　effect　before　the　cause　to　some　extent；　for；　after　all；　the　animal　system　possesses　marvellous　powers　of　adaption；　and　there　is　perhaps　hardly　any　poisonous　vegetable　which　man　might　not　have　learned　to　eat　without　deleterious　effect；　provided　the　experiment　were　made　gradually。　To　a　certain　extent；　then；　the　observed　poisonous　effects　of　numerous　plants　upon　the　human　system　are　to　be　explained　by　the　fact　that　our　ancestors　have　avoided　this　particular　vegetable。　Certain　fruits　and　berries　might　have　come　to　have　been　a　part　of　man's　diet；　had　they　grown　in　the　regions　he　inhabited　at　an　early　day；　which　now　are　poisonous　to　his　system。　This　thought；　however；　carries　us　too　far　afield。　For　practical　purposes；　it　suffices　that　certain　roots；　leaves；　and　fruits　possess　principles　that　are　poisonous　to　the　human　system；　and　that　unless　man　had　learned　in　some　way　to　avoid　these；　our　race　must　have　come　to　disaster。　In　point　of　fact；　he　did　learn　to　avoid　them；　and　such　evidence　implied；　as　has　been　said；　an　elementary　knowledge　of　toxicology。　Coupled　with　this　knowledge　of　things　dangerous　to　the　human　system；　there　must　have　grown　up；　at　a　very　early　day；　a　belief　in　the　remedial　character　of　various　vegetables　as　agents　to　combat　disease。　Here；　of　course；　was　a　rudimentary　therapeutics；　a　crude　principle　of　an　empirical　art　of　medicine。　As　just　suggested；　the　lower　order　of　animals　have　an　instinctive　knowledge　that　enables　them　to　seek　out　remedial　herbs　（though　we　probably　exaggerate　the　extent　of　this　instinctive　knowledge）；　and　if　this　be　true；　man　must　have　inherited　from　his　prehuman　ancestors　this　instinct　along　with　the　others。　That　he　extended　this　knowledge　through　observation　and　practice；　and　came　early　to　make　extensive　use　of　drugs　in　the　treatment　of　disease；　is　placed　beyond　cavil　through　the　observation　of　the　various　existing　barbaric　tribes；　nearly　all　of　whom　practice　elaborate　systems　of　therapeutics。　We　shall　have　occasion　to　see　that　even　within　historic　times　the　particular　therapeutic　measures　employed　were　often　crude；　and；　as　we　are　accustomed　to　say；　unscientific；　but　even　the　crudest　of　them　are　really　based　upon　scientific　principles；　inasmuch　as　their　application　implies　the　deduction　of　principles　of　action　from　previous　observations。　Certain　drugs　are　applied　to　appease　certain　symptoms　of　disease　because　in　the　belief　of　the　medicine…man　such　drugs　have　proved　beneficial　in　previous　similar　cases。　All　this；　however；　implies　an　appreciation　of　the　fact　that　man　is　subject　to　〃natural〃　diseases；　and　that　if　these　diseases　are　not　combated；　death　may　result。　But　it　should　be　understood　that　the　earliest　man　probably　had　no　such　conception　as　this。　Throughout　all　the　ages　of　early　development；　what　we　call　〃natural〃　disease　and　〃natural〃　death　meant　the　onslaught　of　a　tangible　enemy。　A　study　of　this　question　leads　us　to　some　very　curious　inferences。　The　more　we　look　into　the　matter　the　more　the　thought　forces　itself　home　to　us　that　the　idea　of　natural　death；　as　we　now　conceive　it；　came　to　primitive　man　as　a　relatively　late　scientific　induction。　This　thought　seems　almost　startling；　so　axiomatic　has　the　conception　〃man　is　mortal〃　come　to　appear。　Yet　a　study　of　the　ideas　of　existing　savages；　combined　with　our　knowledge　of　the　point　of　view　from　which　historical　peoples　regard　disease；　make　it　more　probable　that　the　primitive　conception　of　human　life　did　not　include　the　idea　of　necessary　death。　We　are　told　that　the　Australian　savage　who　falls　from　a　tree　and　breaks　his　neck　is　not　regarded　as　having　met　a　natural　death；　but　as　having　been　the　victim　of　the　magical　practices　of　the　〃medicine…man〃　of　some　neighboring　tribe。　Similarly；　we　shall　find　that　the　Egyptian　and　the　Babylonian　of　the　early　historical　period　conceived　illness　as　being　almost　invariably　the　result　of　the　machinations　of　an　enemy。　One　need　but　recall　the　superstitious　observances　of　the　Middle　Ages；　and　the　yet　more　recent　belief　in　witchcraft；　to　realize　how　generally　disease　has　been　personified　as　a　malicious　agent　invoked　by　an　unfriendly　mind。　Indeed；　the　phraseology　of　our　present…day　speech　is　still　reminiscent　of　this；　as　when；　for　example；　we　speak　of　an　〃attack　of　fever；〃　and　the　like。　When；　following　out　this　idea；　we　picture　to　ourselves　the　conditions　under　which　primitive　man　lived；　it　will　be　evident　at　once　how　relatively　infrequent　must　have　been　his　observation　of　what　we　usually　term　natural　death。　His　world　was　a　world　of　strife；　he　lived　by　the　chase；　he　saw　animals　kill　one　another；　he　witnessed　the　death　of　his　own　fellows　at　the　hands　of　enemies。　Naturally　enough；　then；　when　a　member　of　his　family　was　〃struck　down〃　by　invisible　agents；　he　ascribed　this　death　also　to　violence；　even　though　the　offensive　agent　was　concealed。　Moreover；　having　very　little　idea　of　the　lapse　of　timebeing　quite　unaccustomed；　that　is；　to　reckon　events　from　any　fixed　eraprimitive　man　cannot　have　gained　at　once　a　clear　conception　of　age　as　applied　to　his　fellows。　Until　a　relatively　late　stage　of　development　made　tribal　life　possible；　it　cannot　have　been　usual　for　man　to　have　knowledge　of　his　grandparents；　as　a　rule　he　did　not　know　his　own　parents　after　he　had　passed　the　adolescent　stage　and　had　been　turned　out　upon　the　world　to　care　for　himself。　If；　then；　certain　of　his　fellow…beings　showed　those　evidences　of　infirmity　which　we　ascribe　to　age；　it　did　not　necessarily　follow　that　he　saw　any　association　between　such　infirmities　and　the　length　of　time　which　those　persons　had　lived。　The　very　fact　that　some　barbaric　nations　retain　the　custom　of　killing　the　aged　and　infirm；　in　itself　suggests　the　possibility　that　this　custom　arose　before　a　clear　conception　had　been　attained　that　such　drags　upon　the　community　would　be　removed　presently　in　the　natural　order　of　things。　To　a　person　who　had　no　clear　conception　of　the　lapse　of　time　and　no　preconception　as　to　the　limited　period　of　man's　life；　the　infirmities　of　age　might　very　naturally　be　ascribed　to　the　repeated　attacks　of　those　inimical　powers　which　were　understood　sooner　or　later　to　carry　off　most　members　of　the　race。　And　coupled　with　this　thought　would　go　the　conception　that　inasmuch　as　some　people　through　luck　had　escaped　the　vengeance　of　all　their　enemies　for　long　periods；　these　same　individuals　might　continue　to　escape　for　indefinite　periods　of　the　future。　There　were　no　written　records　to　tell　primeval　man　of　events　of　long　ago。　He　lived　in　the　present；　and　his　sweep　of　ideas　scarcely　carried　him　back　beyond　the　limits　of　his　individual　memory。　But　memory　is　observed　to　be　fallacious。　It　must　early　have　been　noted　that　some　people　recalled　events　which　other　participants　in　them　had　quite　forgotten；　and　it　may　readily　enough　have　been　inferred　that　those　members　of　the　tribe　who　spoke　of　events　which　others　could　not　recall　were　merely　the　ones　who　were　gifted　with　the　best　memories。　If　these　reached　a　period　when　their　memories　became　vague；　it　did　not　follow　that　their　recollections　had　carried　them　back　to　the　beginnings　of　their　lives。　Indeed；　it　is　contrary　to　all　experience　to　believe　that　any　man　remembers　all　the　things　he　has　once　known；　and　the　observed　fallaciousness　and　evanescence　of　memory　would　thus　tend　to　substantiate　rather　than　to　controvert　the　idea　that　various　members　of　a　tribe　had　been　alive　for　an　indefinite　period。　Without　further　elabor