a history of science-1-第23章

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ch　they　are　derived　and　into　which　they　may　be　again　transformed。　The　fact　that　steam　and　snow　can　be　changed　back　into　water；　and　by　simple　manipulation　cannot　be　changed　into　any　other　substance；　finds；　as　we　now　believe；　its　true　explanation　in　the　fact　that　the　molecular　structure；　as　we　phrase　itthat　is　to　say；　the　ultimate　particle　of　which　water　is　composed；　is　not　changed；　and　this　is　precisely　the　explanation　which　Anaxagoras　gave　of　the　same　phenomena。　For　him　the　unit　particle　of　water　constituted　an　elementary　body；　uncreated；　unchangeable；　indestructible。　This　particle；　in　association　with　like　particles；　constitutes　the　substance　which　we　call　water。　The　same　particle　in　association　with　particles　unlike　itself；　might　produce　totally　different　substancesas；　for　example；　when　water　is　taken　up　by　the　roots　of　a　plant　and　becomes；　seemingly；　a　part　of　the　substance　of　the　plant。　But　whatever　the　changed　association；　so　Anaxagoras　reasoned；　the　ultimate　particle　of　water　remains　a　particle　of　water　still。　And　what　was　true　of　water　was　true　also；　so　he　conceived；　of　every　other　substance。　Gold；　silver；　iron；　earth；　and　the　various　vegetables　and　animal　tissuesin　short；　each　and　every　one　of　all　the　different　substances　with　which　experience　makes　us　familiar；　is　made　up　of　unit　particles　which　maintain　their　integrity　in　whatever　combination　they　may　be　associated。　This　implies；　obviously；　a　multitude　of　primordial　particles；　each　one　having　an　individuality　of　its　own；　each　one；　like　the　particle　of　water　already　cited；　uncreated；　unchangeable；　and　indestructible。　Fortunately；　we　have　the　philosopher's　own　words　to　guide　us　as　to　his　speculations　here。　The　fragments　of　his　writings　that　have　come　down　to　us　（chiefly　through　the　quotations　of　Simplicius）　deal　almost　exclusively　with　these　ultimate　conceptions　of　his　imagination。　In　ascribing　to　him；　then；　this　conception　of　diverse；　uncreated；　primordial　elements；　which　can　never　be　changed；　but　can　only　be　mixed　together　to　form　substances　of　the　material　world；　we　are　not　reading　back　post…Daltonian　knowledge　into　the　system　of　Anaxagoras。　Here　are　his　words：　〃The　Greeks　do　not　rightly　use　the　terms　'coming　into　being'　and　'perishing。'　For　nothing　comes　into　being；　nor；　yet；　does　anything　perish；　but　there　is　mixture　and　separation　of　things　that　are。　So　they　would　do　right　in　calling　'coming　into　being'　'mixture'　and　'perishing'　'separation。'　For　how　could　hair　come　from　what　is　not　hair？　Or　flesh　from　what　is　not　flesh？〃　Elsewhere　he　tells　us　that　（at　one　stage　of　the　world's　development）　〃the　dense；　the　moist；　the　cold；　the　dark；　collected　there　where　now　is　earth；　the　rare；　the　warm；　the　dry；　the　bright；　departed　towards　the　further　part　of　the　aether。　The　earth　is　condensed　out　of　these　things　that　are　separated；　for　water　is　separated　from　the　clouds；　and　earth　from　the　water；　and　from　the　earth　stones　are　condensed　by　the　cold；　and　these　are　separated　farther　from　the　water。〃　Here　again　the　influence　of　heat　and　cold　in　determining　physical　qualities　is　kept　pre…eminently　in　mind。　The　dense；　the　moist；　the　cold；　the　dark　are　contrasted　with　the　rare；　the　warm；　the　dry；　and　bright；　and　the　formation　of　stones　is　spoken　of　as　a　specific　condensation　due　to　the　influence　of　cold。　Here；　then；　we　have　nearly　all　the　elements　of　the　Daltonian　theory　of　atoms　on　the　one　hand；　and　the　nebular　hypothesis　of　Laplace　on　the　other。　But　this　is　not　quite　all。　In　addition　to　such　diverse　elementary　particles　as　those　of　gold；　water；　and　the　rest；　Anaxagoras　conceived　a　species　of　particles　differing　from　all　the　others；　not　merely　as　they　differ　from　one　another；　but　constituting　a　class　by　themselves；　particles　infinitely　smaller　than　the　others；　particles　that　are　described　as　infinite；　self…powerful；　mixed　with　nothing；　but　existing　alone。　That　is　to　say　（interpreting　the　theory　in　the　only　way　that　seems　plausible）；　these　most　minute　particles　do　not　mix　with　the　other　primordial　particles　to　form　material　substances　in　the　same　way　in　which　these　mixed　with　one　another。　But；　on　the　other　hand；　these　〃infinite；　self…powerful；　and　unmixed〃　particles　commingle　everywhere　and　in　every　substance　whatever　with　the　mixed　particles　that　go　to　make　up　the　substances。　There　is　a　distinction　here；　it　will　be　observed；　which　at　once　suggests　the　modern　distinction　between　physical　processes　and　chemical　processes；　or；　putting　it　otherwise；　between　molecular　processes　and　atomic　processes；　but　the　reader　must　be　guarded　against　supposing　that　Anaxagoras　had　any　such　thought　as　this　in　mind。　His　ultimate　mixable　particles　can　be　compared　only　with　the　Daltonian　atom；　not　with　the　molecule　of　the　modern　physicist；　and　his　〃infinite；　self…　powerful；　and　unmixable〃　particles　are　not　comparable　with　anything　but　the　ether　of　the　modern　physicist；　with　which　hypothetical　substance　they　have　many　points　of　resemblance。　But　the　〃infinite；　self…　powerful；　and　unmixed〃　particles　constituting　thus　an　ether…like　plenum　which　permeates　all　material　structures；　have　also；　in　the　mind　of　Anaxagoras；　a　function　which　carries　them　perhaps　a　stage　beyond　the　province　of　the　modern　ether。　For　these　〃infinite；　self　powerful；　and　unmixed〃　particles　are　imbued　with；　and；　indeed；　themselves　constitute；　what　Anaxagoras　terms　nous；　a　word　which　the　modern　translator　has　usually　paraphrased　as　〃mind。〃　Neither　that　word　nor　any　other　available　one　probably　conveys　an　accurate　idea　of　what　Anaxagoras　meant　to　imply　by　the　word　nous。　For　him　the　word　meant　not　merely　〃mind〃　in　the　sense　of　receptive　and　comprehending　intelligence；　but　directive　and　creative　intelligence　as　well。　Again　let　Anaxagoras　speak　for　himself：　〃Other　things　include　a　portion　of　everything；　but　nous　is　infinite；　and　self…powerful；　and　mixed　with　nothing；　but　it　exists　alone；　itself　by　itself。　For　if　it　were　not　by　itself；　but　were　mixed　with　anything　else；　it　would　include　parts　of　all　things；　if　it　were　mixed　with　anything；　for　a　portion　of　everything　exists　in　every　thing；　as　has　been　said　by　me　before；　and　things　mingled　with　it　would　prevent　it　from　having　power　over　anything　in　the　same　way　that　it　does　now　that　it　is　alone　by　itself。　For　it　is　the　most　rarefied　of　all　things　and　the　purest；　and　it　has　all　knowledge　in　regard　to　everything　and　the　greatest　power；　over　all　that　has　life；　both　greater　and　less；　nous　rules。　And　nous　ruled　the　rotation　of　the　whole；　so　that　it　set　it　in　rotation　in　the　beginning。　First　it　began　the　rotation　from　a　small　beginning；　then　more　and　more　was　included　in　the　motion；　and　yet　more　will　be　included。　Both　the　mixed　and　the　separated　and　distinct；　all　things　nous　recognized。　And　whatever　things　were　to　be；　and　whatever　things　were；　as　many　as　are　now；　and　whatever　things　shall　be；　all　these　nous　arranged　in　order；　and　it　arranged　that　rotation；　according　to　which　now　rotate　stars　and　sun　and　moon　and　air　and　aether；　now　that　they　are　separated。　Rotation　itself　caused　the　separation；　and　the　dense　is　separated　from　the　rare；　the　warm　from　the　cold；　the　bright　from　the　dark；　the　dry　from　the　moist。　And　when　nous　began　to　set　things　in　motion；　there　was　separation　from　everything　that　was　in　motion；　all　this　was　made　distinct。　The　rotation　of　the　things　that　were　moved　and　made　distinct　caused　them　to　be　yet　more　distinct。〃＇3＇　Nous；　then；　as　Anaxagoras　conceives　it；　is　〃the　most　rarefied　of　all　things；　and　the　purest；　and　it　has　knowledge　in　regard　to　everything　and　the　greatest　power；　over　all　that　has　life；　both　greater　and　less；　it　rules。〃　But　these　are　postulants　of　omnipresence　and　omniscience。　In　other　words；　nous　is　nothing　less　than　the　omnipotent　artificer　of　the　material　universe。　It　lacks　nothing　of　the　power　of　deity；　save　only　that　we　are　not　assured　that　it　created　the　primordial　particles。　The　creation　of　these　particles　was　a　conception　that　for　Anaxagoras；　as　for　the　modern　Spencer；　lay　beyond　the　range　of　imagination。　Nous　is　the　artificer；　working　with　〃uncreated〃　particles。　Back　of　nous　and　the　particles　lies；　for　an　Anaxagoras　as　for　a　Spencer；　the　Unknowable。　But　nous　itself　is　the　equivalent　of　that　universal　energy　of　motion　which　science　recognizes　as　operating　between　the　particles　of　matter；　and　which　the　theologist　personifies　as　Deity。　It　is　Pantheistic　deity　as　Anaxagoras　conceives　it；　his　may　be　called　the　first　scientific　conception　of　a　non…　anthropomorphic　god。　In　elaborating　this　conception　Anaxagoras　proved　himself　one　of　the　most　remarkable　scientific　dreamers　of　antiquity。　To　have　substituted　for　the　Greek　Pantheon　of　anthropomorphic　deities　the　conception　of　a　non…anthropomorphic　immaterial　and　ethereal　entity；　of　all　things　in　the　world　〃the　most　rarefied　and　the　purest；〃　is　to　have　performed　a　feat　which；　considering　the　age　and　the　environment　in　which　it　was　accomplished；　staggers　the　imagination。　As　a　strictly　scientific　accomplishment　the　great　thinker's　conception　of　primordial　elements　contained　a　germ　of　the　truth　which　was　to　lie　dormant　for　2200　years；　but　which　then；　as　modified　and　vitalized　by　the　genius　of　Dalton；　was　to　dominate　the　new　chemical　science　of　the　nineteenth　century。　If　there　are　intimations　that　the　primordial　element　of　Anaxagoras　and　of　Dalton　may　turn　out　in　the　near　future　to　be　itself　a　compound；　there　will　still　remain　the　yet　finer　particles　of　the　nous　of　Anaxagoras　to　baffle　the　most　subtle　analysis　of　which　to…day's　science　gives　us　any　pre…vision。　All　in　all；　then；　the　work　of　Anaxagoras　must　stand　as　that　of　perhaps　the　most　far…seeing　scientific　imagination　of　pre…Socratic　antiquity。

LEUCIPPUS　AND　DEMOCRITUS　But　we　must　not　leave　this　alluring　field　of　speculation　as　to　the　nature　of　matter　without　referring　to　another　scientific　guess；　which　soon　followed　that　of　Anaxagoras　and　was　destined　to　gain　even　wider　fame；　and　which　in　modern　times　has　been　somewhat　unjustly　held　to　eclipse　the　glory　of　the　other　achievement。　We　mean；　of　course；　the　atomic　theory　of　Leucippus　and　Democritus。　This　theory　reduced　all　matter　to　primordial　elements；　called　atoms　　because　they　are　by　hypothesis　incapable　of　further　division。　These　atoms；　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