2
important. Three aspects of Renaissance natural philosophy in question are very
relevant for the present discussion. The first is that it had two branches—
astronomy and medicine. Astronomy itself was divided into two branches,
astronomia naturalis—the study of the motions of the planet based on
observation and mathematics—and astronima judicialis or astrology—the study
of the supposed ”judgements” of the heavens and the “moral” effects that they
were supposed to produce on all terrestrial things. Medicine was of course the
study of health. However, since heath was supposed to depend on the
knowledge of astronomia judicialis, the study of astrology necessarily became an
integral part of the study of medicine. The relationship between the two
sciences—astronomy and medicine--was thought to be so close that medicine
was often called "philosophical medicine" or "astrological medicine.”
3
The second aspect that deserves our attention is the division of the known
material cosmos into two spheres—the supra-lunar and the sub-lunar. The
planets and the stars belonged to the supra-lunar sphere, and the earth (terra) to
the sub-lunar. The terminology of “supra-lunar” and “sub-lunar “ is owed to the
supposition that the sphere of the Moon--the planet closest to the earth-- marked
the dividing line between heaven and earth.
The third aspect concerned the theory of motion thought to be operating in
the material universe. There were two types of motion—celestial and terrestrial.
Celestial motions--the motions of the planets—were uniform, invariable, and
constant--and terrestrial motions, which were thought to be cyclic, i. e.,
characterized by the process of coming into being, developing, declining, and
Convention