Science exists in the mind; it is nature seen by the reason, and not merely by the senses. The sciences are necessarily progressive in the outward world, because of their internal connection. When a particular fundamental principle is in the process of discovery, it is objective, that is the object contemplated; but when once eliminated it becomes subjective, a new light to act as guide and evolver of kindred principles which lie beyond it, and are of more comprehensive use. The development of man as a race is the unfolding of this inherent dependence of one science upon another, the continuous revelation of that great patrimony of knowledge which is predestined to insure progress, emancipate reason, and entail the highest improvement consistent with a mortal state. When the Greek passed from the outer world of nature in search of wisdom, and descended to the depths of human consciousness, he was no longer traditional; his thought was science, and we can see both its birth and progressiveness. Then only might the world expect that, as Plato says his master once desired, that "Nature should have interpretation according to reason." With Socrates, and the scientific thinkers of his school, philosophy advanced from the realm of nature into the realm of man, and became a moral science. But its early cultivators were copious in abstract principles rather than in practical applications. As Canning said, they were the horses of the chariot of industry, and, going in advance of systemizers, they searched for truth for its own dear sake. Science was indeed beautiful in that serene height of abstract theory it was her first aim to secure, resources so copious and elevated that they might irrigate all lands in their descending flow; as the dove that brought the olive-branch to the ark of man's hopes needed to take a higher and longer flight than the one measured by the tree whence she came.