第 7 节
作者:莫莫言      更新:2022-08-21 16:32      字数:9322
  and     Pythagorean      deductive      dreams     about    the  mysterious      powers     of
  numbers; and of the regular solids。
  Such a people; when they took to studying physical science; would be;
  and     in  fact   were;    incapable      of  Chemistry;      Geognosy;       Comparative
  Anatomy;   or   any   of   that   noble   choir   of   sister   sciences;   which   are   now
  20
  … Page 21…
  ALEXANDRIA AND HER SCHOOLS
  building up the material as well as the intellectual glory of Britain。
  To Astronomy; on the other hand; the pupils of Euclid turned naturally;
  as   to   the   science   which   required   the   greatest   amount   of   their   favourite
  geometry:       but even that they were content to let pass from its inductive
  to   its   deductive   stagenot   as   we   have   done   now;   after   two   centuries   of
  inductive search for the true laws; and their final discovery by Kepler and
  Newton:       but   as   soon   as   Hipparchus   had propounded   any  theory  which
  would do instead of the true laws; content there to stop their experiments;
  and   return   to    their   favourite   work   of   commenting;   deducing;   spinning
  notion out of notion; ad infinitum。
  Still;   they   were   not   all   of   this   temper。 Had   they   been;   they   would
  have discovered; not merely a little; but absolutely nothing。                  For after all;
  if   we   will   consider;   induction   being   the   right   path   to   knowledge;   every
  man; whether he knows it or not; uses induction; more or less; by the mere
  fact   of   his   having   a   human   reason;   and   knowing   anything   at   all;   as   M。
  Jourdain talked prose all his life without being aware of it。
  Aristarchus      is  principally     famous     for   his  attempt     to  discover     the
  distance of the sun as compared with that of the moon。                     His method was
  ingenious enough; but too rough for success; as it depended principally on
  the belief that the line bounding the bright part of the moon was an exact
  straight line。     The result was of course erroneous。              He concluded that the
  sun was 18 times as far as the moon; and not; as we now know; 400; but
  his conclusion; like his conception of the vast extent of the sphere of the
  fixed stars; was far enough in advance of the popular doctrine to subject
  him; according to Plutarch; to a charge of impiety。
  Eratosthenes;   again;   contributed   his   mite   to   the   treasure   of   human
  sciencehis one mite; and yet by that he is better known than by all the
  volumes      which     he   seems    to  have    poured    out;   on  Ethics;    Chronology;
  Criticism on the Old Attic Comedy; and what not; spun out of his weary
  brain    during    a   long   life  of   research    and   meditation。      They      have   all
  perished;like ninety…nine hundredths of the labours of that great literary
  age;   and   perhaps   the   world   is   no   poorer   for   the   loss。   But   one   thing;
  which he attempted on a sound and practical philosophic method; stands;
  and will stand for ever。        And after all; is not that enough to have lived for?
  21
  … Page 22…
  ALEXANDRIA AND HER SCHOOLS
  to have found out one true thing; and; therefore; one imperishable thing; in
  one's   life?    If   each   one   of   us   could   but   say   when   he   died: 〃This   one
  thing I have found out; this one thing I have proved to be possible; this
  one eternal fact I have rescued from Hela; the realm of the formless and
  unknown;〃 how rich one such generation might make the world for ever!
  But such is not the appointed   method。              The finders   are few  and   far
  between; because the true seekers are few and far between; and a whole
  generation has often nothing to show for its existence but one solitary gem
  which some one manoften unnoticed in his timehas picked up for them;
  and so given them 〃a local habitation and a name。〃
  Eratosthenes had heard that in Syene; in Upper Egypt; deep wells were
  enlightened   to   the   bottom   on   the   day   of   the   summer   solstice;   and   that
  vertical objects cast no shadows。
  He   had   before   suggested;   as   is   supposed;   to   Ptolemy   Euergetes;   to
  make   him   the   two   great   copper   armillae;   or   circles   for   determining   the
  equinox;   which   stood   for   centuries   in   〃that   which   is   called   the   Square
  Porch〃probably somewhere in the Museum。                   By these he had calculated
  the obliquity of the ecliptic; closely enough to serve for a thousand years
  after。    That was one work done。            But what had the Syene shadows to do
  with that?      Syene must be under that ecliptic。           On the edge of it。 In short;
  just under the tropic。       Now he had ascertained exactly the latitude of one
  place   on   the   earth's   surface。   He   had   his   known   point   from   whence   to
  start   on   a   world…journey;   and   he   would   use   it;   he   would   calculate   the
  circumference        of  the   earthand    he   did  it。  By     observations     made     at
  Alexandria; he ascertained its latitude compared with that of Syene; and so
  ascertained what proportion to the whole circumference was borne by the
  5000     stadia   between     Alexandria     and    Syene。    He   fell  into  an  error;   by
  supposing       Alexandria     and    Syene    to  be   under    the  same    meridians     of
  longitude:      but that did not prevent his arriving at a fair rough result of
  252;000   stadia31;500   Roman   miles;   considerably   too   much;   but   still;
  before him; I suppose; none knew whether it was 10;000; or 10;000;000。
  The     right   method     having    once    been   found;    nothing    remained      but  to
  employ it more accurately。
  One other great merit of Eratosthenes is; that he first raised Geography
  22
  … Page 23…
  ALEXANDRIA AND HER SCHOOLS
  to the rank of a science。        His Geographica were an organic collection; the
  first   the  world    had   ever    seen;   of  all  the  travels   and   books    of   earth…
  description   heaped   together   in   the   Great   Library;   of   which   he   was   for
  many years the keeper。          He began with a geognostic book; touched on the
  traces of Cataclysms and Change visible on the earth's surface; followed
  by two books; one a mathematical book; the other on political geography;
  and completed by a mapwhich one would like to see:                     but not a trace
  of all remains; save a few quoted fragments …
  We are such stuff As dreams are made of。
  But   if   Eratosthenes   had   hold   of   eternal   fact   and   law   on   one   point;
  there was a contemporary who had hold of it in more than one。                        I mean
  Archimedes; of whom; as I have said; we must speak as of an Alexandrian。
  It was as a mechanician; rather than as an astronomer; that he gained his
  reputation。      The stories of his Hydraulic Screw; the Great Ship which he
  built for Hiero; and launched by means of machinery; his crane; his war…
  engines;     above    all  his  somewhat      mythical     arrangement      of  mirrors;    by
  which   he   set   fire   to   ships   in   the  harbourall   these;   like   the  story   of   his
  detecting the alloy in Hiero's crown; while he himself was in the bath; and
  running   home   undressed   shouting   'Greek   text:           eureeka'all   these   are
  schoolboys' tales。        To the thoughtful person it is the method of the man
  which   constitutes   his   real   greatness;   that   power   of   insight   by   which   he
  solved the two great problems of the nature of the lever and of hydrostatic
  pressure; which form the basis of all static and hydrostatic science to this
  day。     And     yet  on   that  very    question    of  the   lever   the  great   mind    of
  Aristotle babblesneither sees the thing itself; nor the way towards seeing
  it。   But   since  Archimedes   spoke;   the   thing   seems   self…evident   to   every
  schoolboy。       There is something to me very solemn in such a fact as this。
  It   brings   us   down   to   some   of   the  very  deepest   questions   of   metaphysic。
  This    mental     insight   of  which     we   boast    so  much;     what    is  it?  Is   it
  altogether a process of our own brain and will?                If it be; why have so few
  the   power;   even   among   men   of   power;   and   they   so   seldom?         If   brain
  alone were what was wanted; what could not Aristotle have discovered?
  Or is it that no man c