obtain equally in astronomy and chemistry. The phenomena of the living body must in the end be subject to the principles of physics, and physics must in the end become mechanics. But sensation, attention, and feeling can never be reduced to matter in motion. A complete correlation between mental and physical changes. may be established, but the most perfect knowledge of the processes of the brain would of itself throw no light on the nature of thought. The blind man will not learn to see by studying the changes taking place in the combustion of a candle. Psychology can never be made a branch of physiology.
Laboratories of psychology are for the study of mental processes. It would not be possible in a single article to give an account of what has been accomplished by experimental psychology, nor would tables, curves, and mathematical formulæ prove interesting reading. "The plain man," in Bishop Berkeley's phrase, "undebauched by learning," is apt to ask. What is the good of all this? It may, therefore, be better to give several examples of the practical application of the results of experimental psychology. Pure science is not, indeed, an art whose end is to produce changes in the course of Nature. Astronomy is commonly regarded as the noblest of the sciences, but we can not alter the orbits of the planets, and the higher astronomy is not useful in the affairs of daily life. Science is an end in itself, as are the fine arts. It is good because it satisfies mental needs, and makes life better worth the while. But material science, while searching for truth, has not failed to contribute to the practical needs of society. Its applications in the arts and manufactures have guided the course of civilization. One man to-day can do the work which required ten men a hundred years ago, and the poor have now comforts and opportunities which were formerly not within the reach of the rich. In like manner we shall probably find that more exact knowledge of the mind will have many applications in pedagogy, in political science, in medicine, in the fine arts, and, indeed, in the whole conduct of life.
Let us consider pedagogy. Our methods of education have been greatly altered in the past few years, and more changes will follow. But we go forward blindly, not seeing the way, often retracing our steps. The poor children contribute to the progress of educational methods somewhat as the frog contributes to the progress of physiology. But we may hope to replace vague surmises with exact knowledge. In our laboratories of psychology we can test the senses and faculties of children. We can determine whether the course of study is developing or stunting fundamental characteristics, such as accuracy of perception, quickness of thought, memory, reasoning, etc. We can learn what methods best strengthen each of these faculties without injuring the others.
