a history of science-1-第29节

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toms；　making　up　the　entire　material　universe；　are　in　this　theory　conceived　as　qualitatively　identical；　differing　from　one　another　only　in　size　and　perhaps　in　shape。　The　union　of　different…sized　atoms　in　endless　combinations　produces　the　diverse　substances　with　which　our　senses　make　us　familiar。　Before　we　pass　to　a　consideration　of　this　alluring　theory；　and　particularly　to　a　comparison　of　it　with　the　theory　of　Anaxagoras；　we　must　catch　a　glimpse　of　the　personality　of　the　men　to　whom　the　theory　owes　its　origin。　One　of　these；　Leucippus；　presents　so　uncertain　a　figure　as　to　be　almost　mythical。　Indeed；　it　was　long　questioned　whether　such　a　man　had　actually　lived；　or　whether　be　were　not　really　an　invention　of　his　alleged　disciple；　Democritus。　Latterday　scholarship；　however；　accepts　him　as　a　real　personage；　though　knowing　scarcely　more　of　him　than　that　he　was　the　author　of　the　famous　theory　with　which　his　name　was　associated。　It　is　suggested　that　he　was　a　wanderer；　like　most　philosophers　of　his　time；　and　that　later　in　life　he　came　to　Abdera；　in　Thrace；　and　through　this　circumstance　became　the　teacher　of　Democritus。　This　fable　answers　as　well　as　another。　What　we　really　know　is　that　Democritus　himself；　through　whose　writings　and　teachings　the　atomic　theory　gained　vogue；　was　born　in　Abdera；　about　the　year　460　B。C。that　is　to　say；　just　about　the　time　when　his　great　precursor；　Anaxagoras；　was　migrating　to　Athens。　Democritus；　like　most　others　of　the　early　Greek　thinkers；　lives　in　tradition　as　a　picturesque　figure。　It　is　vaguely　reported　that　he　travelled　for　a　time；　perhaps　in　the　East　and　in　Egypt；　and　that　then　he　settled　down　to　spend　the　remainder　of　his　life　in　Abdera。　Whether　or　not　he　visited　Athens　in　the　course　of　his　wanderings　we　do　not　know。　At　Abdera　he　was　revered　as　a　sage；　but　his　influence　upon　the　practical　civilization　of　the　time　was　not　marked。　He　was　pre…eminently　a　dreamer　and　a　writer。　Like　his　confreres　of　the　epoch；　he　entered　all　fields　of　thought。　He　wrote　voluminously；　but；　unfortunately；　his　writings　have；　for　the　most　part；　perished。　The　fables　and　traditions　of　a　later　day　asserted　that　Democritus　had　voluntarily　put　out　his　own　eyes　that　he　might　turn　his　thoughts　inward　with　more　concentration。　Doubtless　this　is　fiction；　yet；　as　usual　with　such　fictions；　it　contains　a　germ　of　truth；　for　we　may　well　suppose　that　the　promulgator　of　the　atomic　theory　was　a　man　whose　mind　was　attracted　by　the　subtleties　of　thought　rather　than　by　the　tangibilities　of　observation。　Yet　the　term　〃laughing　philosopher；〃　which　seems　to　have　been　universally　applied　to　Democritus；　suggests　a　mind　not　altogether　withdrawn　from　the　world　of　practicalities。　So　much　for　Democritus　the　man。　Let　us　return　now　to　his　theory　of　atoms。　This　theory；　it　must　be　confessed；　made　no　very　great　impression　upon　his　contemporaries。　It　found　an　expositor；　a　little　later；　in　the　philosopher　Epicurus；　and　later　still　the　poet　Lucretius　gave　it　popular　expression。　But　it　seemed　scarcely　more　than　the　dream　of　a　philosopher　or　the　vagary　of　a　poet　until　the　day　when　modern　science　began　to　penetrate　the　mysteries　of　matter。　When；　finally；　the　researches　of　Dalton　and　his　followers　had　placed　the　atomic　theory　on　a　surer　footing　as　the　foundation　of　modern　chemistry；　the　ideas　of　the　old　laughing　philosopher　of　Abdera；　which　all　along　had　been　half　derisively　remembered；　were　recalled　with　a　new　interest。　Now　it　appeared　that　these　ideas　had　curiously　foreshadowed　nineteenth…century　knowledge。　It　appeared　that　away　back　in　the　fifth　century　B。C。　a　man　had　dreamed　out　a　conception　of　the　ultimate　nature　of　matter　which　had　waited　all　these　centuries　for　corroboration。　And　now　the　historians　of　philosophy　became　more　than　anxious　to　do　justice　to　the　memory　of　Democritus。　It　is　possible　that　this　effort　at　poetical　restitution　has　carried　the　enthusiast　too　far。　There　is；　indeed；　a　curious　suggestiveness　in　the　theory　of　Democritus；　there　is　philosophical　allurement　in　his　reduction　of　all　matter　to　a　single　element；　it　contains；　it　may　be；　not　merely　a　germ　of　the　science　of　the　nineteenth…century　chemistry；　but　perhaps　the　germs　also　of　the　yet　undeveloped　chemistry　of　the　twentieth　century。　Yet　we　dare　suggest　that　in　their　enthusiasm　for　the　atomic　theory　of　Democritus　the　historians　of　our　generation　have　done　something　less　than　justice　to　that　philosopher's　precursor；　Anaxagoras。　And　one　suspects　that　the　mere　accident　of　a　name　has　been　instrumental　in　producing　this　result。　Democritus　called　his　primordial　element　an　atom；　Anaxagoras；　too；　conceived　a　primordial　element；　but　he　called　it　merely　a　seed　or　thing；　he　failed　to　christen　it　distinctively。　Modern　science　adopted　the　word　atom　and　gave　it　universal　vogue。　It　owed　a　debt　of　gratitude　to　Democritus　for　supplying　it　the　word；　but　it　somewhat　overpaid　the　debt　in　too　closely　linking　the　new　meaning　of　the　word　with　its　old　original　one。　For；　let　it　be　clearly　understood；　the　Daltonian　atom　is　not　precisely　comparable　with　the　atom　of　Democritus。　The　atom；　as　Democritus　conceived　it；　was　monistic；　all　atoms；　according　to　this　hypothesis；　are　of　the　same　substance；　one　atom　differs　from　another　merely　in　size　and　shape；　but　not　at　all　in　quality。　But　the　Daltonian　hypothesis　conceived；　and　nearly　all　the　experimental　efforts　of　the　nineteenth　century　seemed　to　prove；　that　there　are　numerous　classes　of　atoms；　each　differing　in　its　very　essence　from　the　others。　As　the　case　stands　to…day　the　chemist　deals　with　seventy…odd　substances；　which　he　calls　elements。　Each　one　of　these　substances　is；　as　he　conceives　it；　made　up　of　elementary　atoms　having　a　unique　personality；　each　differing　in　quality　from　all　the　others。　As　far　as　experiment　has　thus　far　safely　carried　us；　the　atom　of　gold　is　a　primordial　element　which　remains　an　atom　of　gold　and　nothing　else；　no　matter　with　what　other　atoms　it　is　associated。　So；　too；　of　the　atom　of　silver；　or　zinc；　or　sodiumin　short；　of　each　and　every　one　of　the　seventy…odd　elements。　There　are；　indeed；　as　we　shall　see；　experiments　that　suggest　the　dissolution　of　the　atomthat　suggest；　in　short；　that　the　Daltonian　atom　is　misnamed；　being　a　structure　that　may；　under　certain　conditions；　be　broken　asunder。　But　these　experiments　have；　as　yet；　the　warrant　rather　of　philosophy　than　of　pure　science；　and　to…day　we　demand　that　the　philosophy　of　science　shall　be　the　handmaid　of　experiment。　When　experiment　shall　have　demonstrated　that　the　Daltonian　atom　is　a　compound；　and　that　in　truth　there　is　but　a　single　true　atom；　which；　combining　with　its　fellows　perhaps　in　varying　numbers　and　in　different　special　relations；　produces　the　Daltonian　atoms；　then　the　philosophical　theory　of　monism　will　have　the　experimental　warrant　which　to…day　it　lacks；　then　we　shall　be　a　step　nearer　to　the　atom　of　Democritus　in　one　direction；　a　step　farther　away　in　the　other。　We　shall　be　nearer；　in　that　the　conception　of　Democritus　was；　in　a　sense；　monistic；　farther　away；　in　that　all　the　atoms　of　Democritus；　large　and　small　alike；　were　considered　as　permanently　fixed　in　size。　Democritus　postulated　all　his　atoms　as　of　the　same　substance；　differing　not　at　all　in　quality；　yet　he　was　obliged　to　conceive　that　the　varying　size　of　the　atoms　gave　to　them　varying　functions　which　amounted　to　qualitative　differences。　He　might　claim　for　his　largest　atom　the　same　quality　of　substance　as　for　his　smallest；　but　so　long　as　he　conceived　that　the　large　atoms；　when　adjusted　together　to　form　a　tangible　substance；　formed　a　substance　different　in　quality　from　the　substance　which　the　small　atoms　would　make　up　when　similarly　grouped；　this　concession　amounts　to　the　predication　of　difference　of　quality　between　the　atoms　themselves。　The　entire　question　reduces　itself　virtually　to　a　quibble　over　the　word　quality；　So　long　as　one　atom　conceived　to　be　primordial　and　indivisible　is　conceded　to　be　of　such　a　nature　as　necessarily　to　produce　a　different　impression　on　our　senses；　when　grouped　with　its　fellows；　from　the　impression　produced　by　other　atoms　when　similarly　grouped；　such　primordial　atoms　do　differ　among　themselves　in　precisely　the　same　way　for　all　practical　purposes　as　do　the　primordial　elements　of　Anaxagoras。　The　monistic　conception　towards　which　twentieth…　century　chemistry　seems　to　be　carrying　us　may　perhaps　show　that　all　the　so…called　atoms　are　compounded　of　a　single　element。　All　the　true　atoms　making　up　that　element　may　then　properly　be　said　to　have　the　same　quality；　but　none　the　less　will　it　remain　true　that　the　combinations　of　that　element　that　go　to　make　up　the　different　Daltonian　atoms　differ　from　one　another　in　quality　in　precisely　the　same　sense　in　which　such　tangible　substances　as　gold；　and　oxygen；　and　mercury；　and　diamonds　differ　from　one　another。　In　the　last　analysis　of　the　monistic　philosophy；　there　is　but　one　substance　and　one　quality　in　the　universe。　In　the　widest　view　of　that　philosophy；　gold　and　oxygen　and　mercury　and　diamonds　are　one　substance；　and；　if　you　please；　one　quality。　But　such　refinements　of　analysis　as　this　are　for　the　transcendental　philosopher；　and　not　for　the　scientist。　Whatever　the　allurement　of　such　reasoning；　we　must　for　the　purpose　of　science　let　words　have　a　specific　meaning；　nor　must　we　let　a　mere　word…jugglery　blin