ly absurd, is the outcome of a process of reasoning starting from a premise, which premise is an absurd fear or doubt. There is nothing wrong in the act or in the process of logical conclusion, granting the premise. The premise is, however, a false idea forced upon the consciousness so intensely as to carry conviction. It is quite analogous to a hallucination in the domain of sensory perception, but it belongs to the ideational sphere, or to the emotional sphere of mind. You will have noticed that the same sort of doubts occur to different minds.
It may be said that such fears, doubts, or impulses might occur to any one, but could be at once discarded. In the fact that they are not discarded, that there is a lack of self-control and mental balance which allows of their taking possession of the mind, lies the proof that in such cases there is a defect of mental development. Such cases show us clearly how important it is to sound normal mental action that a firm control over the tendencies of the mind to wander foolishly, to indulge in absurd doubts and fears, should be constantly exercised; and such control should be inculcated upon the child's mind as it develops, lest the individual come to yield to or to foolishly fear these abnormal impulses. That self-control is the highest quality of mind is evident from the fact that the first evidence of mental deterioration is seen in a beginning failure of this power.
You are all familiar with the fact that many acts of an insane kind are spontaneous, and not the result of a process of logical reasoning. Thus, a sudden impulse to steal, or to set fire to an object, may come upon one and lead to the act, for which no explanation can be given except the sudden onset of an abnormal and irresistible desire. These acts are in a way as unexpected as the hallucinations or the doubts or fears, and like them must be ascribed to sudden excitation of brain functions beyond our control from internal causes, the effects of disease. Such acts are not of much interest to the student of psychology, for they do not involve a process of thought. They are most commonly observed, however, in persons of the degenerate type which we have been studying. In these persons, then, of degenerate type we observe an imperfect mental equilibrium, which prevents a successful resistance of sudden impulses, and a successful suppression of sudden doubts and fears, and which thus deprives the victim of his liberty of action in spite of his conscious knowledge that the impulses or doubts are absurd or wrong. From time to time in their lives these persons suffer for weeks and months from their mental distress; then, for unknown reasons, they may be free from it, but usually it returns, and it is an annoyance through the entire life. One of the most interesting studies of the mental processes of a person thus afflicted has been published by Prof. Royce,