at impulse to investigation
then. His genius in promoting an evolution doctrine as regards 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. The
execution of Bruno had occurred in his childhood, and in the midst of
his career he had watched the Galileo struggle in all its stages. He had
seen his own works condemned by university after university under the
direction of theologians, and placed upon the Roman Index. 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 and thwarted 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 honours, but the
priests--ruling in the confessionals and pulpits--would not allow
him the privilege of aiding his fellow-men to ascertain God's truths
revealed in Nature.

Spinoza, Hume, and Kant may also be mentioned as among those whose
thinking, even when mistaken, might have done much to aid in the
development of a truer theory had not the theologic atmosphere of their
times been so unpropitious; but a few years after Leibnitz's death came
in France a thinker in natural science of much less influence than any
of these, 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,
though