[Sidenote: Revolt against Aristotle]
The prologue to the drama of the new thought was revolt against Aristotle. "The master of them who know" had become, after the definite acceptance of his works as standard texts in the universities of the thirteenth century, an inspired and infallible authority {637} for all science. With him were associated the schoolmen who debated the question of realism versus nominalism. But as the mind of man grew and advanced, what had been once the brace became a galling bond. All parties united to make common cause against the Stagyrite. The Italian Platonists attacked him in the name of their, and his, master. Luther opined that no one had ever understood Aristotle's meaning, that the ethics of that "damned heathen" directly contradicted Christian virtue, that any potter would know more of natural science than he, and that it would be well if he who had started the debate on realism and nominalism had never been born. Catholics like Usingen protested at the excessive reverence given to Aristotle at the expense of Christ. Finally, the French scientist Peter Ramus [Sidenote: Ramus, c. 1515-72] advanced the thesis at the University of Paris that everything taught by Aristotle was false. No authority, he argued, is superior to reason, for it is reason which creates and determines authority.
[Sidenote: Effect of science on philosophy]
In place of Aristotle men turned to nature. "Whosoever in discussion adduces authority uses not intellect but memory," said Leonardo. Vives urged that experiment was the only road to truth. The discoveries of natural laws led to a new conception of external reality, independent of man's wishes and egocentric theories. It also gave rise to the conception of uniformity of law. Copernicus sought and found a mathematical unity in the heavens. It was, above all else, his astronomy that fought the battle of, and won the victory for, the new principles of research. Its glory was not so much its positive addition to knowledge, great as that was, but its mode of thought. By pure reason a new system was established and triumphed over the testimony of the senses and of all {638} previous authority, even that which purported to be revelation. Man was reduced to a creature of law; God was defined as an expression of law.
How much was man's imagination touched, how was his whole thought and purpose changed by the Copernican discovery! No longer lord of a little, bounded world, man crept as a parasite on a grain of dust spinning eternally through endless space. And with the humiliation came a great exaltation. For this tiny creature could now seal the stars and bind the Pleiades and sound each deep abyss that held a sun. What new sublimity of thought, what greatness of soul was not his! To Copernicus belongs properly the praise lavished by Lucretius on Epicurus, of having burst the flaming bounds of the world and of having made man equal to heaven. The history of the past, the religion of the present, the science of the future—all ideas were transmuted, all values reversed by this new and wonderful hypothesis.
But all this, of course, was but dimly sensed by the contemporaries of Copernicus. What they really felt was the new compulsion of natural law and the necessity of causation. Leonardo was led thus far by his study of mathematics, which he regarded as the key to natural science. He even went so far as to define time as a sort of non-geometrical space.
[Sidenote: Theory of knowledge]
Two things were necessary to a philosophy in harmony with the scientific view; the first was a new theory of knowledge, the second was a new conception of the ultimate reality in the universe. Paracelsus contributed to the first in the direction of modern empiricism, by defending understanding as that which comprehended exactly the thing that the hand touched and the eyes saw. Several immature attempts were made at scientific skepticism. That of Cornelius Agrippa—De incertitudine et vanitate scientiarum et {639} artium atque excellentia Verbi Dei declamatio—can hardly be taken seriously, as it was regarded by the author himself rather as a clever paradox. Francis Sanchez, on the other hand, formulated a tenable theory of the impossibility of knowing anything. A riper theory of perception, following Paracelsus and anticipating Leibnitz, was that of Edward Digby, based on the notion of the active correspondence between mind and matter.
[Sidenote: The ultimate reality]
To the thinker of the sixteenth century the solution of the question of the ultimate reality seemed to demand some form of identification of the world-soul with matter. Paracelsus and Gilbert both felt in the direction of hylozoism, or the theory of the animation of all things. If logically carried out, as it was not by them, this would have meant that everything was God. The other alternative, that God was everything, was developed by a remarkable man, who felt for the new science the enthusiasm of a religious convert, Giordano Bruno.