Men thought, spoke and acted for long ages before they began to reflect on the ways in which they did so; and, when they did begin to reflect, it was long before they discovered the principles on which they thought, spoke and acted, or recognised them as the principles on which man must speak, if he is to speak intelligibly; on which, as laws of thought, he must think, if he is to think correctly; and on which, as laws of morality, he must act, if he is to act as he should act. But though many thousands of years elapsed before he recognised these laws, they were, all the time, the laws on which he had to think, speak and act, and did actually think, speak and act, so far as he did so correctly. When, then, we speak of the evolution of thought, speech and action, we cannot mean that the laws of thought, for instance, were in the beginning different from what they are now, and only gradually came to be what they are at present. That would be just the same as saying that the law of gravitation did not operate in the way described by Newton until Newton formulated the law. The fact is that science has its evolution, just as thought, speech and action have. Man gradually and with much effort discovers laws of science, as he discovers the laws of thought, speech and action. In neither case does he make the laws; all that he does in either case is to come to recognise that they are there. But the recognition is a process, a slow process, attended by many mistakes and set-backs. And this slow process of the gradual recognition or discovery of fundamental laws, or first principles, is the process in which the evolution of science, as well as the evolution of thought, speech and action, consists. It is the process by which the laws that are at the bottom of man's thought, speech and action, and are fundamental to them, tend to rise to the surface of consciousness.