a history of science-1-第43章

按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！


al　centre　appeared　on　the　south　shore　of　the　Mediterranean。　This　was　the　city　of　Alexandria；　a　city　which　Alexander　the　Great　had　founded　during　his　brief　visit　to　Egypt；　and　which　became　the　capital　of　Ptolemy　Soter　when　he　chose　Egypt　as　his　portion　of　the　dismembered　empire　of　the　great　Macedonian。　Ptolemy　had　been　with　his　master　in　the　East；　and　was　with　him　in　Babylonia　when　he　died。　He　had　therefore　come　personally　in　contact　with　Babylonian　civilization；　and　we　cannot　doubt　that　this　had　a　most　important　influence　upon　his　life；　and　through　him　upon　the　new　civilization　of　the　West。　In　point　of　culture；　Alexandria　must　be　regarded　as　the　successor　of　Babylon；　scarcely　less　directly　than　of　Greece。　Following　the　Babylonian　model；　Ptolemy　erected　a　great　museum　and　began　collecting　a　library。　Before　his　death　it　was　said　that　he　had　collected　no　fewer　than　two　hundred　thousand　manuscripts。　He　had　gathered　also　a　company　of　great　teachers　and　founded　a　school　of　science　which；　as　has　just　been　said；　made　Alexandria　the　culture…centre　of　the　world。　Athens　in　the　day　of　her　prime　had　known　nothing　quite　like　this。　Such　private　citizens　as　Aristotle　are　known　to　have　had　libraries；　but　there　were　no　great　public　collections　of　books　in　Athens；　or　in　any　other　part　of　the　Greek　domain；　until　Ptolemy　founded　his　famous　library。　As　is　well　known；　such　libraries　had　existed　in　Babylonia　for　thousands　of　years。　The　character　which　the　Ptolemaic　epoch　took　on　was　no　doubt　due　to　Babylonian　influence；　but　quite　as　much　to　the　personal　experience　of　Ptolemy　himself　as　an　explorer　in　the　Far　East。　The　marvellous　conquering　journey　of　Alexander　had　enormously　widened　the　horizon　of　the　Greek　geographer；　and　stimulated　the　imagination　of　all　ranks　of　the　people；　It　was　but　natural；　then；　that　geography　and　its　parent　science　astronomy　should　occupy　the　attention　of　the　best　minds　in　this　succeeding　epoch。　In　point　of　fact；　such　a　company　of　star…gazers　and　earth…measurers　came　upon　the　scene　in　this　third　century　B。C。　as　had　never　before　existed　anywhere　in　the　world。　The　whole　trend　of　the　time　was　towards　mechanics。　It　was　as　if　the　greatest　thinkers　had　squarely　faced　about　from　the　attitude　of　the　mystical　philosophers　of　the　preceding　century；　and　had　set　themselves　the　task　of　solving　all　the　mechanical　riddles　of　the　universe；　They　no　longer　troubled　themselves　about　problems　of　〃being〃　and　〃becoming〃；　they　gave　but　little　heed　to　metaphysical　subtleties；　they　demanded　that　their　thoughts　should　be　gauged　by　objective　realities。　Hence　there　arose　a　succession　of　great　geometers；　and　their　conceptions　were　applied　to　the　construction　of　new　mechanical　contrivances　on　the　one　hand；　and　to　the　elaboration　of　theories　of　sidereal　mechanics　on　the　other。　The　wonderful　company　of　men　who　performed　the　feats　that　are　about　to　be　recorded　did　not　all　find　their　home　in　Alexandria；　to　be　sure；　but　they　all　came　more　or　less　under　the　Alexandrian　influence。　We　shall　see　that　there　are　two　other　important　centres；　one　out　in　Sicily；　almost　at　the　confines　of　the　Greek　territory　in　the　west；　the　other　in　Asia　Minor；　notably　on　the　island　of　Samosthe　island　which；　it　will　be　recalled；　was　at　an　earlier　day　the　birthplace　of　Pythagoras。　But　whereas　in　the　previous　century　colonists　from　the　confines　of　the　civilized　world　came　to　Athens；　now　all　eyes　turned　towards　Alexandria；　and　so　improved　were　the　facilities　for　communication　that　no　doubt　the　discoveries　of　one　coterie　of　workers　were　known　to　all　the　others　much　more　quickly　than　had　ever　been　possible　before。　We　learn；　for　example；　that　the　studies　of　Aristarchus　of　Samos　were　definitely　known　to　Archimedes　of　Syracuse；　out　in　Sicily。　Indeed；　as　we　shall　see；　it　is　through　a　chance　reference　preserved　in　one　of　the　writings　of　Archimedes　that　one　of　the　most　important　speculations　of　Aristarchus　is　made　known　to　us。　This　illustrates　sufficiently　the　intercommunication　through　which　the　thought　of　the　Alexandrian　epoch　was　brought　into　a　single　channel。　We　no　longer；　as　in　the　day　of　the　earlier　schools　of　Greek　philosophy；　have　isolated　groups　of　thinkers。　The　scientific　drama　is　now　played　out　upon　a　single　stage；　and　if　we　pass；　as　we　shall　in　the　present　chapter；　from　Alexandria　to　Syracuse　and　from　Syracuse　to　Samos；　the　shift　of　scenes　does　no　violence　to　the　dramatic　unities。　Notwithstanding　the　number　of　great　workers　who　were　not　properly　Alexandrians；　none　the　less　the　epoch　is　with　propriety　termed　Alexandrian。　Not　merely　in　the　third　century　B。C。；　but　throughout　the　lapse　of　at　least　four　succeeding　centuries；　the　city　of　Alexander　and　the　Ptolemies　continued　to　hold　its　place　as　the　undisputed　culture…centre　of　the　world。　During　that　period　Rome　rose　to　its　pinnacle　of　glory　and　began　to　decline；　without　ever　challenging　the　intellectual　supremacy　of　the　Egyptian　city。　We　shall　see；　in　a　later　chapter；　that　the　Alexandrian　influences　were　passed　on　to　the　Mohammedan　conquerors；　and　every　one　is　aware　that　when　Alexandria　was　finally　overthrown　its　place　was　taken　by　another　Greek　city；　Byzantium　or　Constantinople。　But　that　transfer　did　not　occur　until　Alexandria　had　enjoyed　a　longer　period　of　supremacy　as　an　intellectual　centre　than　had　perhaps　ever　before　been　granted　to　any　city；　with　the　possible　exception　of　Babylon。

EUCLID　（ABOUT　300　B。C。）　Our　present　concern　is　with　that　first　wonderful　development　of　scientific　activity　which　began　under　the　first　Ptolemy；　and　which　presents；　in　the　course　of　the　first　century　of　Alexandrian　influence；　the　most　remarkable　coterie　of　scientific　workers　and　thinkers　that　antiquity　produced。　The　earliest　group　of　these　new　leaders　in　science　had　at　its　head　a　man　whose　name　has　been　a　household　word　ever　since。　This　was　Euclid；　the　father　of　systematic　geometry。　Tradition　has　preserved　to　us　but　little　of　the　personality　of　this　remarkable　teacher；　but；　on　the　other　hand；　his　most　important　work　has　come　down　to　us　in　its　entirety。　The　Elements　of　Geometry；　with　which　the　name　of　Euclid　is　associated　in　the　mind　of　every　school…boy；　presented　the　chief　propositions　of　its　subject　in　so　simple　and　logical　a　form　that　the　work　remained　a　textbook　everywhere　for　more　than　two　thousand　years。　Indeed　it　is　only　now　beginning　to　be　superseded。　It　is　not　twenty　years　since　English　mathematicians　could　deplore　the　fact　that；　despite　certain　rather　obvious　defects　of　the　work　of　Euclid；　no　better　textbook　than　this　was　available。　Euclid's　work；　of　course；　gives　expression　to　much　knowledge　that　did　not　originate　with　him。　We　have　already　seen　that　several　important　propositions　of　geometry　had　been　developed　by　Thales；　and　one　by　Pythagoras；　and　that　the　rudiments　of　the　subject　were　at　least　as　old　as　Egyptian　civilization。　Precisely　how　much　Euclid　added　through　his　own　investigations　cannot　be　ascertained。　It　seems　probable　that　he　was　a　diffuser　of　knowledge　rather　than　an　originator；　but　as　a　great　teacher　his　fame　is　secure。　He　is　credited　with　an　epigram　which　in　itself　might　insure　him　perpetuity　of　fame：　〃There　is　no　royal　road　to　geometry；〃　was　his　answer　to　Ptolemy　when　that　ruler　had　questioned　whether　the　Elements　might　not　be　simpli