though it is in form, leaves no
serious doubt that Aristarchus of Samos not only propounded the view
that the earth revolves both on its own axis and around the sun, but
that he correctly removed the great stumbling-block in the way of this
theory by adding that the distance of the fixed stars was infinitely
greater than the dimensions of the earth's orbit. Even the world of
philosophy was not yet ready for this conception, and, so far from
seeing the reasonableness of the explanation, we find Ptolemy arguing
against the rotation of the earth on grounds which careful observations
of the phenomena around him would have shown to be ill-founded.

Physical science, if we can apply that term to an uncoordinated body of
facts, was successfully cultivated from the earliest times. Something
must have been known of the properties of metals, and the art of
extracting them from their ores must have been practised, from the time
that coins and medals were first stamped. The properties of the most
common compounds were discovered by alchemists in their vain search for
the philosopher's stone, but no actual progress worthy of the name
rewarded the practitioners of the black art.

Perhaps the first approach to a correct method was that of Archimedes,
who by much thinking worked out the law of the lever, reached the
conception of the centre of gravity, and demonstrated the first
principles of hydrostatics. It is remarkable that he did not extend his
researches into the phenomena of motion, whether spontaneous or
produced by force. The stationary condition of the human intellect is
most strikingly illustrated by the fact that not until the time of
Leonardo was any substantial advance made on his discovery. To sum up
in one sentence the most characteristic feature of ancient and medieval
science, we see a notable contrast between the precision of thought
implied in the construction and demonstration of geometrical theorems
and the vague indefinite character of the ideas of natural phenomena
generally, a contrast which did not disappear until the foundations of
modern science began to be laid.

We should miss the most essential point of the difference between
medieval and modern learning if we looked upon it as mainly a
difference either in the precision or the amount of knowledge. The
development of both of these qualities would, under any circumstances,
have been slow and gradual, but sure. We can hardly suppose that any
one generati