outside the Church, slowly to gain strength. On all sides, in every field, men were making discoveries which caused the general theological view to appear more and more inadequate.
In the first half of the seventeenth century Descartes seemed about to take for a time the leadership of human thought; his theories, however superseded now, gave a great impulse to investigation then. His genius in promoting an evolution doctrine as regarded the mechanical formation of the solar system was great, and his mode of thought strengthened the current of evolutionary doctrine generally; but his constant dread of persecution, both from Catholics and Protestants, led him steadily to veil his thoughts and even to suppress them. He had watched the Galileo struggle in all its stages; he had seen his own books condemned by university after university under the direction of theologians, and placed upon the index of prohibited books. Although he gave new and striking arguments to prove the existence of God, and humbled himself before the Jesuits, he was condemned by Catholics and Protestants alike; since Roger Bacon, perhaps, no great thinker had been so completely abased by theological oppression.
Near the close of the same century another great thinker, Leibnitz, though not propounding any full doctrine on evolution, gave it an impulse by suggesting a view contrary to the sacrosanct belief in the immutability of species—that is, to the pious doctrine that every species in the animal kingdom now exists as it left the hands of the Creator, the naming process by Adam, and the door of Noah's ark.
His punishment at the hands of the Church came a few years later, when, in 1712, the Jesuits defeated his attempt to found an Academy of Science at Vienna; the imperial authorities covered him with honors, but the priests—ruling in the confessionals and pulpits—would not allow him the privilege of aiding his fellowmen to ascertain God's truths revealed in Nature.
A few years after Leibnitz's death came in France a thinker in natural science of much less influence, but who made a decided step forward.
Early in the eighteenth century Benoist de Maillet, a man of the world, but a wide observer and close thinker upon Nature, began meditating especially upon the origin of animal forms, and was led into the idea of the transformation of species and so into a theory of evolution, which in some important respects anticipated modern ideas. He definitely conceived the production of existing species by the modification of their predecessors, and he plainly accepted one of the fundamental maxims of modern geology—that the structure of the globe must be studied in the light of the present course of Nature.