a history of science-2-第10章

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s　life。　He　himself　tells　us　that　he　had　even　questioned　whether　it　were　not　better　for　him　to　confine　himself　to　such　verbal　teaching；　following　thus　the　example　of　Pythagoras。　Just　as　his　life　was　drawing　to　a　close；　he　decided　to　pursue　the　opposite　course；　and　the　first　copy　of　his　work　is　said　to　have　been　placed　in　his　hands　as　he　lay　on　his　deathbed。　The　violent　opposition　which　the　new　system　met　from　ecclesiastical　sources　led　subsequent　commentators　to　suppose　that　Copernicus　had　delayed　publication　of　his　work　through　fear　of　the　church　authorities。　There　seems；　however；　to　be　no　direct　evidence　for　this　opinion。　It　has　been　thought　significant　that　Copernicus　addressed　his　work　to　the　pope。　It　is；　of　course；　quite　conceivable　that　the　aged　astronomer　might　wish　by　this　means　to　demonstrate　that　he　wrote　in　no　spirit　of　hostility　to　the　church。　His　address　to　the　pope　might　have　been　considered　as　a　desirable　shield　precisely　because　the　author　recognized　that　his　work　must　needs　meet　with　ecclesiastical　criticism。　Be　that　as　it　may；　Copernicus　was　removed　by　death　from　the　danger　of　attack；　and　it　remained　for　his　disciples　of　a　later　generation　to　run　the　gauntlet　of　criticism　and　suffer　the　charges　of　heresy。　The　work　of　Copernicus；　published　thus　in　the　year　1543　at　Nuremberg；　bears　the　title　De　Orbium　Coelestium　Revolutionibus。　It　is　not　necessary　to　go　into　details　as　to　the　cosmological　system　which　Copernicus　advocated；　since　it　is　familiar　to　every　one。　In　a　word；　he　supposed　the　sun　to　be　the　centre　of　all　the　planetary　motions；　the　earth　taking　its　place　among　the　other　planets；　the　list　of　which；　as　known　at　that　time；　comprised　Mercury；　Venus；　the　Earth；　Mars；　Jupiter；　and　Saturn。　The　fixed　stars　were　alleged　to　be　stationary；　and　it　was　necessary　to　suppose　that　they　are　almost　infinitely　distant；　inasmuch　as　they　showed　to　the　observers　of　that　time　no　parallax；　that　is　to　say；　they　preserved　the　same　apparent　position　when　viewed　from　the　opposite　points　of　the　earth's　orbit。　But　let　us　allow　Copernicus　to　speak　for　himself　regarding　his　system；　His　exposition　is　full　of　interest。　We　quote　first　the　introduction　just　referred　to；　in　which　appeal　is　made　directly　to　the　pope。　〃I　can　well　believe；　most　holy　father；　that　certain　people；　when　they　hear　of　my　attributing　motion　to　the　earth　in　these　books　of　mine；　will　at　once　declare　that　such　an　opinion　ought　to　be　rejected。　Now；　my　own　theories　do　not　please　me　so　much　as　not　to　consider　what　others　may　judge　of　them。　Accordingly；　when　I　began　to　reflect　upon　what　those　persons　who　accept　the　stability　of　the　earth；　as　confirmed　by　the　opinion　of　many　centuries；　would　say　when　I　claimed　that　the　earth　moves；　I　hesitated　for　a　long　time　as　to　whether　I　should　publish　that　which　I　have　written　to　demonstrate　its　motion；　or　whether　it　would　not　be　better　to　follow　the　example　of　the　Pythagoreans；　who　used　to　hand　down　the　secrets　of　philosophy　to　their　relatives　and　friends　only　in　oral　form。　As　I　well　considered　all　this；　I　was　almost　impelled　to　put　the　finished　work　wholly　aside；　through　the　scorn　I　had　reason　to　anticipate　on　account　of　the　newness　and　apparent　contrariness　to　reason　of　my　theory。　〃My　friends；　however；　dissuaded　me　from　such　a　course　and　admonished　me　that　I　ought　to　publish　my　book；　which　had　lain　concealed　in　my　possession　not　only　nine　years；　but　already　into　four　times　the　ninth　year。　Not　a　few　other　distinguished　and　very　learned　men　asked　me　to　do　the　same　thing；　and　told　me　that　I　ought　not；　on　account　of　my　anxiety；　to　delay　any　longer　in　consecrating　my　work　to　the　general　service　of　mathematicians。　〃But　your　holiness　will　perhaps　not　so　much　wonder　that　I　have　dared　to　bring　the　results　of　my　night　labors　to　the　light　of　day；　after　having　taken　so　much　care　in　elaborating　them；　but　is　waiting　instead　to　hear　how　it　entered　my　mind　to　imagine　that　the　earth　moved；　contrary　to　the　accepted　opinion　of　mathematiciansnay；　almost　contrary　to　ordinary　human　understanding。　Therefore　I　will　not　conceal　from　your　holiness　that　what　moved　me　to　consider　another　way　of　reckoning　the　motions　of　the　heavenly　bodies　was　nothing　else　than　the　fact　that　the　mathematicians　do　not　agree　with　one　another　in　their　investigations。　In　the　first　place；　they　are　so　uncertain　about　the　motions　of　the　sun　and　moon　that　they　cannot　find　out　the　length　of　a　full　year。　In　the　second　place；　they　apply　neither　the　same　laws　of　cause　and　effect；　in　determining　the　motions　of　the　sun　and　moon　and　of　the　five　planets；　nor　the　same　proofs。　Some　employ　only　concentric　circles；　others　use　eccentric　and　epicyclic　ones；　with　which；　however；　they　do　not　fully　attain　the　desired　end。　They　could　not　even　discover　nor　compute　the　main　thingnamely；　the　form　of　the　universe　and　the　symmetry　of　its　parts。　It　was　with　them　as　if　some　should；　from　different　places；　take　hands；　feet；　head；　and　other　parts　of　the　body；　which；　although　very　beautiful；　were　not　drawn　in　their　proper　relations；　and；　without　making　them　in　any　way　correspond；　should　construct　a　monster　instead　of　a　human　being。　〃Accordingly；　when　I　had　long　reflected　on　this　uncertainty　of　mathematical　tradition；　I　took　the　trouble　to　read　again　the　books　of　all　the　philosophers　I　could　get　hold　of；　to　see　if　some　one　of　them　had　not　once　believed　that　there　were　other　motions　of　the　heavenly　bodies。　First　I　found　in　Cicero　that　Niceties　had　believed　in　the　motion　of　the　earth。　Afterwards　I　found　in　Plutarch；　likewise；　that　some　others　had　held　the　same　opinion。　This　induced　me　also　to　begin　to　consider　the　movability　of　the　earth；　and；　although　the　theory　appeared　contrary　to　reason；　I　did　so　because　I　knew　that　others　before　me　had　been　allowed　to　assume　rotary　movements　at　will；　in　order　to　explain　the　phenomena　of　these　celestial　bodies。　I　was　of　the　opinion　that　I；　too；　might　be　permitted　to　see　whether；　by　presupposing　motion　in　the　earth；　more　reliable　conclusions　than　hitherto　reached　could　not　be　discovered　for　the　rotary　motions　of　the　spheres。　And　thus；　acting　on　the　hypothesis　of　the　motion　which；　in　the　following　book；　I　ascribe　to　the　earth；　and　by　long　and　continued　observations；　I　have　finally　discovered　that　if　the　motion　of　the　other　planets　be　carried　over　to　the　relation　of　the　earth　and　this　is　made　the　basis　for　the　rotation　of　every　star；　not　only　will　the　phenomena　of　the　planets　be　explained　thereby；　but　also　the　laws　and　the　size　of　the　stars；　all　their　spheres　and　the　heavens　themselves　will　appear　so　harmoniously　connected　that　nothing　could　be　changed　in　any　part　of　them　without　confusion　in　the　remaining　parts　and　in　the　whole　universe。　I　do　not　doubt　that　clever　and　learned　men　will　agree　with　me　if　they　are　willing　fully　to　comprehend　and　to　consider　the　proofs　which　I　advance　in　the　book　before　us。　In　order；　however；　that　both　the　learned　and　the　unlearned　may　see　that　I　fear　no　man's　judgment；　I　wanted　to　dedicate　these；　my　night　labors；　to　your　holiness；　rather　than　to　any　one　else；　because　you；　even　in　this　remote　corner　of　the　earth　where　I　live；　are　held　to　be　the　greatest　in　dignity　of　station　and　in　love　for　all　sciences　and　for　mathematics；　so　that　you；　through　your　position　and　judgment；　can　easily　suppress　the　bites　of　slanderers；　although　the　proverb　says　that　there　is　no　remedy　against　the　bite　of　calumny。〃

In　chapter　X。　of　book　I。；　〃On　the　Order　of　the　Spheres；〃　occurs　a　more　detailed　presentation　of　the　system；　as　follows：　〃That　which　Martianus　Capella；　and　a　few　other　Latins；　very　well　knew；　appears　to　me　extremely　noteworthy。　He　believed　that　Venus　and　Mercury　revolve　about　the　sun　as　their　centre　and　that　they　cannot　go　farther　away　from　it　than　the　circles　of　their　orbits　permit；　since　they　do　not　revolve　about　the　earth　like　the　other　planets。　According　to　this　theory；　then；　Mercury's　orbit　would　be　included　within　that　of　Venus；　which　is　more　than　twice　as　great；　and　would　find　room　enough　within　it　for　its　revolution。　〃If；　acting　upon　this　supposition；　we　connect　Saturn；　Jupiter；　and　Mars　with　the　same　centre；　keeping　in　mind　the　greater　extent　of　their　orbits；　which　include　the　earth's　sphere　besides　those　of　Mercury　and　Venus；　we　cannot　fail　to　see　the　explanation　of　the　regular　order　of　their　motions。　He　is　certain　that　Saturn；　Jupiter；　and　Mars　are　always　nearest　the　earth　when　they　rise　in　the　eveningthat　is；　when　they　appear　over　against　the　sun；　or　the　earth　stands　between　them　and　the　sunbut　that　they　are　farthest　from　the　earth　when　they　set　in　the　eveningthat　is；　when　we　have　the　sun　between　them　and　the　earth。　This　proves　sufficiently　that　their　centre　belongs　to　the　sun　and　is　the　same　about　which　the　orbits　of　Venus　and　Mercury　circle。　Since；　however；　all　have　one　centre；　it　is　necessary　for　the　space　intervening　between　the　orbits　of　Venus　and　Mars　to　include　the　earth　with　her　accompanying　moon　and　all　that　is　beneath　the　moon；　for　the　moon；　which　stands　unquestionably　nearest　the　earth；　can　in　no　way　be　separated　from　her；　especially　as　there　is　sufficient　room　for　the　moon　in　the　aforesaid　space。　Hence　we　do　not　hesitate　to　claim　that　the　whole　system；　which　includes　the　moon　with　the　earth　for　its　centre；　makes　the　round　of　that　great　circle　between　t