If science, then, can only with difficulty lift from visible nature the veils that hide the truth—and even this is often beyond its power—no wonder it is confronted with still greater obstacles when it approaches the truths that are beyond visible nature. Moreover, it is an old truth that here it is led not by reason only, but also, and even more energetically, by self-interest. “Most men,” says _Cicero_, “are swayed in their judgments by either love or hatred, likes or dislikes” (De Oratore, II, 42). If this is the nature of human science, its adepts would be badly deceiving themselves, if, in the pride of learning, they would reject every correction, even proudly pushing aside the hand of God that reaches down into the darkness of man’s intellectual life to offer its guidance. He who realizes that he is in danger of losing his way in the dark, will not reject a reliable guide; and he who fears to stumble will not refuse a helping hand. Self-knowledge is the sister of wisdom, and the mother of modesty. Freedom. Such, then, is science: not the goddess that emanated from the head of immortal Jove, but the offspring of the puny mind of man, bone of his bone and flesh of his flesh. And this science cries for freedom. It would be free and act freely; it urges its claim in the name of truth, which must not be slighted; in the name of the progress of civilization, which must not be hindered. _Freedom_ clearly means nothing less than to be untrammeled and free from restraint, from fetter and check, in action, thought, and desire. The prisoner is free when his chains drop off, a people is free when it has cast off the yoke of serfdom, the eagle is free and can spread out its wings in lofty flight when not bound down to the earth. Science, therefore, should be free in its activity from bond, fetter, and restraint. Does this mean it must be free from _all_ restraint and law? Should the historian be given the right to make _Solon_ a member of the French Academy, or of the heroes of Troy mediæval knights? Should the scientist be given the right to break every rule of logic, to ignore all progress, and perhaps in his capriciousness return to the four elements of _Aristotle_, or the astronomical chart of primitive ages? Nobody demands this. No, science must be bound by the _truth_. Freedom indeed should not mean lawlessness. Science remains bound by the general laws of logic, and by positive facts. Truth is the irremovable barrier set in restraint of the freedom of everything, even of scientific thought. The freedom of science therefore can only be freedom from _unreasonable_ restraint and fetters; from such that hinder it unreasonably in its inquiry after the truth, and in the communication of the results of its investigation. _It should be free, not from the internal bondage of truth, but from the restraint by external authority_, the restraint which would hinder it, in