data, as we may call them, come to us without exertion or activity on our part; it is the intellect which gives them meaning, which interprets them, which makes them the apprehension or awareness of objects or things. And the active part that the intellect plays is also a process of selection. This is evident if we reflect upon the universal form which our intellectual activity takes, namely, attention. It is in the act of attention that we are conscious of mental activity, and attention is essentially selection--the selection of an interest. Besides the natural selection that is effected by our senses and the conscious selection that is manifest in attention, there is also a more or less arbitrary selection that our intellect performs in marking out the lines of our practical interest and possible action. In this work of selection the intellect makes the world conform to the necessities of our action. So far we have looked at our intellectual endowment from the standpoint of ordinary common-sense experience. Let us now consider the philosophical theory based on this view, which explains the nature of knowledge by showing its purpose. The intellect not only selects, but in selecting transforms the reality. It presents us with knowledge that indeed corresponds with reality, for it is essentially a view of reality, but also in selecting it marks out divisions, and gives to reality a form that is determined by practical interest. The same reality is different to different individuals and to different species according to their practical interests. {66} The practical end which the human intellect serves is to present us with a field for our life activity. This is the real world for us, as we know it, real objects in a real space. Had we no other way of knowing but that of our intellect we should not know the life which is active within us as it is really lived, we should be as those who, standing outside, watch a movement, and not as those who are carried along in the movement and experience it from within. In life and intellect we have the counterpart of reality and appearance. Life is not something that changes; it is the change of which the something is the appearance. Life is the reality of which all things, as we understand them, are the appearances, and on account of which they appear. The solid things in space and time are not in reality what they appear; they are views of the reality. The intellect guided by our practical interest presents reality under this form of solid spatial things. Clearly, then, if this view be true, the whole world, as it is presented to us and thought of by us, is an illusion. Our science is not unreal, but it is a transformed reality. The illusions may be useful, may, indeed, be necessary and indispensable, but nevertheless it is illusion.