But the autocratic enforcement of antiquated dogma, and the serf-like submission to authority, could not go on forever. A revolution came, even within the ranks of the theologians themselves. Giordano Bruno (1548-1600) revived the teachings of Aristotle, and combined them with theories, and combined them with ideas secured by omnivorous reading of Greek, Arabic, and Oriental writings. He undoubtedly had some conception of evolution, compares the intelligence of man and various of the lower animals, and recognizes a physical relationship between them. In geology he was essentially modern, arguing against the six thousand years of Bible chronology, and maintaining that conditions of his day were the same, fundamentally, as those during ancient periods of the earth’s history--a doctrine which he probably borrowed from the Arabian, Avicenna. Before considering others of the philosophers who became, during the sixteenth and seventeenth centuries, the sponsors of the evolution idea, we may well pause to glance at the general state of learning throughout Europe at the beginning of that period. Just as any idea is a product of the men who advocate it, so is its development dependant upon the state of culture in the regions where it is being fostered. We must, therefore, consider the outstanding features of that environment in order to understand the true significance of the progress made along the line in which we are principally interested. Universities in Europe were founded at the beginning of the twelfth century, following those established by the Arabs[2]. Oxford, the most noted university of England, was founded about a century later. For a long time after this, authority still held almost unchallenged sway. Naturalists were mainly compilers, repeating what had been said and done before them, and carefully avoiding anything new. But in the first half of the sixteenth century there sprang up, in the Italian university town of Padua, an important school of anatomy. In 1619 Harvey, an English physiologist, discovered[3] the circulation of blood, and applied the method of experimental study in zoology. This one piece of work was of far more importance than all of his contributions to physiology--of which he is usually considered the real founder--for it gave to scientists the one almost infallible method of securing information. In the latter half of the seventeenth century the study of microscopic organisms was begun, and the foundations of a logical classification of animals was laid by Ray.