without the aid of either superstition or charlatanry. CHAPTER XVI THE POWERS OF THE MIND (Sets forth the fact that knowledge is freedom and ignorance is slavery, and what science means to the people.) We have now completed a brief survey of the mind and its powers. Whatever we may have proved or failed to prove, this much we may say with assurance: the reader who has followed our brief sketch attentively has been disabused of any idea he may have held that he knows it all; and this is always the first step towards knowledge. The mind is the instrument whereby our race has lifted itself out of beasthood. It is the instrument whereby we hold ourselves above the forces which seek to drag us down, and whereby we shall lift ourselves higher, if higher we are to go. How shall we protect this precious instrument? How shall we complete our mastery of it? What are the laws of the conduct of the mind? The process of the mind is one of groping outward after new facts, and digesting and assimilating them, as the body gropes after and digests and assimilates food. The senses bring us new impressions, and we take these and analyze them, tear them into the parts which compose them, compare them with previous sensations, recognize difference in things which seem to be alike, and resemblances in things which seem to be different; we classify them, and provide them with names, which are, as it were, handles for the mind to grasp. Above all, we seek for causes; those chains of events which make what we know as order in the world of phenomena. And when the mind has what seems to be a cause, it proceeds to test it according to methods it has worked out, the rules and principles of experimental science. It is a comparatively small number of sensations which the body brings to the mind of itself; it is a narrow world in which we should live if our minds adopted a passive attitude toward life. But some minds possess what we call curiosity; they set out upon their own impulse to explore life; they discover new laws and make new experiences and new sensations for themselves. The mind forms an idea, and at first, after the fashion of the ancient Greek philosophers, it glorifies that idea and sets it in the seat of divinity. But presently comes the empirical method, which refuses authority to any idea unless it can stand the test of experiment, and prove that it corresponds with reality. Nowadays the thinker amasses his facts, and forms a theory to explain them, and then proceeds to try out this theory by the most rigid method that he or his critics can devise. If the theory doesn't "work"--that is, if it doesn't explain all the facts and stand all the tests--it is thrown away like a worn-out shoe. So little by little a body of knowledge is built up which is real knowledge; which will serve us in our daily lives, which we can use as foundation-stones in the structure of our civilization.