The scientific
renaissance that followed Bacon's time marks a change in
philosophical beliefs every bit as significant as that in the arts.
Men such as Leonardo da Vinci, who approached science from a
practical standpoint, foreshadowed many of the ideas of Galileo,
Kepler and Newton, but did not write up their discoveries in any
coherent form. The best we have is Leonardo's collection of
notebooks, which indicate his studies and philosophies. In one
sense, Leonardo was all experiment and represented the opposite
extreme to the Greeks.
Leonardo held an
opposing view of motion to Aristotle. Aristotle claimed that
nothing moved unless it was made to do so by God, the Unmoved
Mover. Leonardo suggests the opposite, writing in his
notebook, 'Nothing perceptible by the senses is able to move
itself… every body has a weight in the direction of the
movement.' In other words, matter has an innate tendency to move in
a certain direction unless stopped. This anticipates the notion of
inertia first postulated by Galileo some half-century later and
eventually formalised by Newton.