somewhat of mystery; that the scene may not be shifted too
suddenly from the vague, impersonal East to the individualism of
Europe.

All of this, however, must not be taken as casting any doubt upon
the existence of Thales as a real person. Even the dates of his
life--640 to 546 B.C.--may be accepted as at least approximately
trustworthy; and the specific discoveries ascribed to him
illustrate equally well the stage of development of Greek
thought, whether Thales himself or one of his immediate disciples
were the discoverer. We have already mentioned the feat which was
said to have given Thales his great reputation. That Thales was
universally credited with having predicted the famous eclipse is
beyond question. That he actually did predict it in any precise
sense of the word is open to doubt. At all events, his prediction
was not based upon any such precise knowledge as that of the
modern astronomer. There is, indeed, only one way in which he
could have foretold the eclipse, and that is through knowledge of
the regular succession of preceding eclipses. But that knowledge
implies access on the part of some one to long series of records
of practical observations of the heavens. Such records, as we
have seen, existed in Egypt and even more notably in Babylonia.
That these records were the source of the information which
established the reputation of Thales is an unavoidable inference.
In other words, the magical prevision of the father of Greek
thought was but a reflex of Oriental wisdom. Nevertheless, it
sufficed to establish Thales as the father of Greek astronomy. In
point of fact, his actual astronomical attainments would appear
to have been meagre enough. There is nothing to show that he
gained an inkling of the true character of the solar system. He
did not even recognize the sphericity of the earth, but held,
still following the Oriental authorities, that the world is a
flat disk. Even his famous cosmogonic guess, according to which
water is the essence of all things and the primordial element out
of which the earth was developed, is but an elaboration of the
Babylonian conception.

When we turn to the other field of thought with which the name of
Thales is associated--namely, geometry--we again find evidence of
the Oriental influence. The science of geometry, Herodotus
assures us, was invented in Egypt. It was there an eminently
practical science, being applied, as the name literally suggests,
to the measurement of the earth's surface. Herodotus tells us
that the Egyptians were obliged to cultivate the science because
the periodical inundations washed away the boundary-lines between
their farms. The primitive geometer, then, was a surveyor. The
Egyptian records, as now revealed to us, show that the science
had not been carried far in the land of its birth. The Egyptian
geometer was able to measure irregular pieces of land only
approximately. He never fully grasped the idea of the
perpendicular as the true index of measurement for the triangle,
but based his calculations upon measurements of the actual side
of that figure. Nevertheless, he had learned to square the circle
with a close approximation to the truth, and, in general, his
measurement sufficed for all his practical needs. Just how much
of the geometrical knowledge which added to the fame of Thales
was borrowed directly from the Egyptians, and how much he
actually created we cannot be sure. Nor is the question raised in
disparagement of his genius. Receptivity is the first
prerequisite to progressive thinking, and that Thales reached out
after and imbibed portions of Oriental wisdom argues in itself
for the creative character of his genius. Whether borrower of
originator, however, Thales is credited with the expression of
the following geometrical truths:

1. That the circle is bisected by its diameter.

2. That the angles at the base of an isosceles triangle are
equal.

3. That when two straight lines cut each other the vertical
opposite angles are equal.

4. That the angle in a semicircle is a right angle.

5. That one side and one acute angle of a right-angle triangle
determine the other sides of the triangle.

It was by the application of the last of these principles that
Thales is said to have performed the really notable feat of
measuring the distance of a ship from the shore, his method being
precisely the same in principle as that by which the guns are
sighted on a modern man-of-war. Another practical demonstration
which Thales was credited with making, and to which also his
geometrical studies led him, was the measurement of any tall
object, such as a pyramid or building or tree, by means of its
shadow. The method, though simple enough, was ingenious. It
consisted merely in observing the moment of the day when a
perpendicular stick casts a shadow equal to its own length.
Obviously the tree or monument would also cast a shadow equal to
its own height at the same moment. It remains then but to measure
the length of this shadow to determine the height of the object.
Such feats as this evidence the practicality of the genius of
Thales. They suggest that Greek science, guided by imagination,
was starting on the high-road of observation. We are told that
Thales conceived for the first time the geometry of lines, and
that this, indeed, constituted his real advance upon the
Egyptians. We are told also that he conceived the eclipse of the
sun as a purely natural phenomenon, and that herein lay his
advance upon the Chaldean point of view. But if this be true


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