h of these departments of knowledge that no one
man has the temerity to attempt to master them all. But it was different
in those days of beginnings. Then the methods of observation were still
crude, and it was quite the custom for a thinker of forceful personality
to find an eager following among disciples who never thought of putting
his theories to the test of experiment. The great lesson that true
science in the last resort depends upon observation and measurement,
upon compass and balance, had not yet been learned, though here and
there a thinker like Anaxagoras had gained an inkling of it.

For the moment, indeed, there in Attica, which was now, thanks to that
outburst of Periclean culture, the centre of the world's civilization,
the trend of thought was to take quite another direction. The very year
which saw the birth of Democritus at Abdera, and of Hippocrates, marked
also the birth, at Athens, of another remarkable man, whose influence it
would scarcely be possible to over-estimate. This man was Socrates. The
main facts of his history are familiar to every one. It will be recalled
that Socrates spent his entire life in Athens, mingling everywhere with
the populace; haranguing, so the tradition goes, every one who
would listen; inculcating moral lessons, and finally incurring the
disapprobation of at least a voting majority of his fellow-citizens. He
gathered about him a company of remarkable men with Plato at their head,
but this could not save him from the disapprobation of the multitudes,
at whose hands he suffered death, legally administered after a public
trial. The facts at command as to certain customs of the Greeks at this
period make it possible to raise a question as to whether the alleged
"corruption of youth," with which Socrates was charged, may not have had
a different implication from what posterity has preferred to ascribe
to it. But this thought, almost shocking to the modern mind and seeming
altogether sacrilegious to most students of Greek philosophy, need not
here detain us; neither have we much concern in the present connection
with any part of the teaching of the martyred philosopher. For the
historian of metaphysics, Socrates marks an epoch, but for the historian
of science he is a much less consequential figure.

Similarly regarding Plato, the aristocratic Athenian who sat at the
feet of Socrates, and through whose writings the teachings of the master
found widest currency. Some students