The senses are intensely practical in their relation to life. The processes of natural selection make and keep them so. Only those phases of reality which our ancestors could render into action are shown to us by our senses. If we can do nothing in any case, we know nothing about it. The senses tell us essential truth about rocks and trees, food and shelter, friends and enemies. They answer no problems in chemistry. They tell us nothing about atom or molecule. They give us no ultimate facts. Whatever is so small that we cannot handle it is too small to be seen. Whatever is too distant to be reached is not truthfully reported. The "X-rays" of light we cannot see, because our ancestors could not deal with them. The sun and stars, the clouds and the sky are not at all what they appear to be. The truthfulness of the senses fails as the square of the distance increases. Were it not so, we should be smothered by truth; we should be overwhelmed by the multiplicity of our own sensations, and truthful response in action would become impossible. Hyperaesthesia of any or all of the senses is a source of confusion, not of strength. It is essentially a phase of disease, and it shows itself in ineffectiveness, not in increased power. Besides the actual sensations, the so-called realities, the brain retains also the sensations which have been, and which are not wholly lost. Memory-pictures crowd the mind, mingling with pictures which are brought in afresh by the senses. The force of suggestion causes the mental states or conditions of one person to repeat themselves in another. Abnormal conditions of the brain itself furnish another series of feelings with which the brain must deal. Moreover, the brain is charged with impulses to action passed on from generation to generation, surviving because they are useful. With all these arises the necessity for choice as a function of the mind. The mind must neglect or suppress all sensations which it cannot weave into action. The dog sees nothing that does not belong to its little world. The man in search of mushrooms "tramples down oak-trees in his walks." To select the sensations that concern us is the basis of the power of attention. The suppression of undesired actions is a function of the will. To find data for choice among the possible motor responses is a function of the intellect. Intellectual persistency is the essence of individual character. As the conditions of life become more complex, it becomes necessary for action to be more carefully selected. Wisdom is the parent of virtue. Knowing what should be done logically precedes doing it. Good impulses and good intentions do not make action right or safe. In the long run, action is tested not by its motives, but by its results.