field of natural knowledge were brought to a standstill by the decay
and disruption of the Roman Empire, the consequent disorganisation of
society, and the diversion of men's thoughts from sublunary matters to
the problems of the supernatural world suggested by Christian dogma in
the Middle Ages. And, notwithstanding sporadic attempts to recall men
to the investigation of nature, here and there, it was not until the
fifteenth and sixteenth centuries that physical science made a new
start, founding itself, at first, altogether upon that which had been
done by the Greeks. Indeed, it must be admitted that the men of the
Renaissance, though standing on the shoulders of the old philosophers,
were a long time before they saw as much as their forerunners had
done.

The first serious attempts to carry further the unfinished work of
Archimedes, Hipparchus, and Ptolemy, of Aristotle and of Galen,
naturally enough arose among the astronomers and the physicians. For
the imperious necessity of seeking some remedy for the physical ills
of life had insured the preservation of more or less of the wisdom of
Hippocrates and his successors, and, by a happy conjunction of
circumstances, the Jewish and the Arabian physicians and philosophers
escaped many of the influences which, at that time, blighted natural
knowledge in the Christian world. On the other hand, the superstitious
hopes and fears which afforded countenance to astrology and to alchemy
also sheltered astronomy and the germs of chemistry. Whether for this,
or for some better reason, the founders of the schools of the Middle
Ages included astronomy, along with geometry, arithmetic, and music,
as one of the four branches of advanced education; and, in this
respect, it is only just to them to observe that they were far in
advance of those who sit in their seats. The school men considered no
one to be properly educated unless he were acquainted with, at any