were the natural motions. Because the natural
motions were different, the natures had to be different, and these
different natures led to a universe and a concept of space neither of
which were Aristotelian. One no longer had a central reference point
for absolute space; there was no "motor essentialis" focused upon the
earth but one had only the mutual motion of the heavenly bodies. The
natural distinction between heaven and earth was gone, for the earth
was no longer an inert recipient but a source of wonder, and so the
stage was set for the universe of Giordano Bruno.[213] The
Aristotelian philosophy of nature was used to justify a new cosmology,
but there was no break with the past such as one finds in Galileo and
Kepler. Instead he followed the chimera of the world organism, as
Paracelsus had, and of the world soul, as Bruno had. Consequently
Gilbert's physiology did not enter into the main stream of science.

[212] Because the earth has the same nature as a celestial
globe, its revolution and circular inertia require no more
explanation than those of any other heavenly body.

[213] One wonders if Bruno might not have been another of the
stimuli for Gilbert. The latter's interest in magnetism began
shortly before Bruno visited England and lectured on his
interpretation of the Copernican theory.

Yet this is not to deny Gilbert's services to natural philosophy.
Although not all of his experimental distinction between electric and
magnetic forces has been retained, still, some of it has. His "orbis
virtutis" was to become a field of force, and his class of electrics,
insulators of electricity. His practice of arming a loadstone was to
be of considerable importance in the period before the invention of
the electromagnet. His limited recognition of the mutual nature of
forces and their quantitative basis in mass was ultimately to appear
in Newton's second and third laws of motion. In spite of the
weaknesses of the method of analogy, Gilbert's experimental model of
the terrella to interpret the earth's magnetism was as much a
contribution to scientific method as to the theory of magnetism.

Consequently, in spite of an explanation of electricity and magnetism
that one would be amused to find in a textbook today, we can still
read his _De magnete_ with interest and profit. But more important
than his scientific speculations, is the insight he can give us into a
Renaissance philosophy of na