A whole system of education could be arranged with bird life as material for arousing and fixing the interest of the learner. But this is not our purpose. A whole system should take in all of the universe that is capable of interesting the learner. Our purpose is to take the most intensely absorbing field and show how it may be tilled. Birds are used because so much more and better activity is to be secured by using them as the material for school work than from any other. Why birds are so commanding to the growing mind will become clear to one who will patiently follow the thought in the remainder of this article. In avoiding technical terms the statement has been weakened, but it is believed that those who would enjoy the reading better if the terms were technical and closely accurate do not need to have the matter stated to them at all. Hence the statement is made in the terms of common speech with the object in mind of giving the reasons to those not much accustomed to the terms used by writers on psychological topics. The mind is somewhat like the eye. It takes in whatever is before it. It is never concentrated upon one object alone, but has to occupy itself to some extent with the surroundings of the object. It is impossible to fix the mind, or the attention, exclusively upon one thing. We frequently ask our pupils to do this, but it is impossible. The mind at any one instant resembles the surface of a wave of water, part of what it carries is low, another part higher, and some other things are highest. But few things can be at or near the crest at once. Many things are around the base. As with the eye a few objects are at or near the focus, many things are where they are sensed but are not in the supreme position. And as the wave of water runs along its course so the mind moves forward. It will either run directly away from the subject or it will turn the subject over and carry it along in continually changing aspects. The mind cannot stand still. It cannot keep anything more than an instant except by turning the thing about and perceiving it in relation to other things. We still consider we have the thing in mind after we have ceased to think of it as a whole and pass on to thinking of its relations to other things. The mind differs from the wave of water in that it is not extensive to the right and left of its course. It is like a hill with a small crest that can hold but few objects upon its surface. When we say we are thinking profoundly upon a subject we mean that that subject and its connections are continuously upon the crest of the wave, and that unrelated things are either not in the mind at all or they are at least not at the focus.