In 1892 I was asked by the Harvard Corporation to give a few public lectures on psychology to the Cambridge teachers. The talks now printed form the substance of that course, which has since then been delivered at various places to various teacher-audiences. I have found by experience that what my hearers seem least to relish is analytical technicality, and what they most care for is concrete practical application. So I have gradually weeded out the former, and left the latter unreduced; and now, that I have at last written out the lectures, they contain a minimum of what is deemed 'scientific' in psychology, and are practical and popular in the extreme. Some of my colleagues may possibly shake their heads at this; but in taking my cue from what has seemed to me to be the feeling of the audiences I believe that I am shaping my book so as to satisfy the more genuine public need. Teachers, of course, will miss the minute divisions, subdivisions, and definitions, the lettered and numbered headings, the variations of type, and all the other mechanical artifices on which they are accustomed to prop their minds. But my main desire has been to make them conceive, and, if possible, reproduce sympathetically in their imagination, the mental life of their pupil as the sort of active unity which he himself feels it to be.