To regard man as actuated by reason is a hopeless error. Instinct forms the mainspring of his action, and reason is used to carry out the promptings of instinct. It must be remembered, however, that instinct does not function in crude physical forms only. Man possesses emotions and intellect as well as a body, and upon each plane of his being the instincts express themselves appropriately, functioning emotionally and intellectually as well as physically. A man uses his wits as well as his muscles in the struggle for self-preservation, and the sex instinct is not exhausted by the physical act of procreation. Emphasis is laid upon this point, because herein lies the key to the practical application of psychology to human life. The emotions have their sources in the instincts; indeed, an emotion may be said to be the subjective aspect of an instinct. If an instinct is achieving its aim, we feel pleasure; if it is being frustrated, we feel pain; and if we anticipate its frustration, we feel fear. Whenever there is emotion, some underlying instinct must have been stirred into activity. It will thus be seen how predominating is the influence exerted by the instincts upon our lives; they may, in fact, be considered the mainsprings of motive. At one time psychology busied itself with the reasoning processes, and looked upon man as a rational being, and indeed the man in the street still considers himself as such, but the researches of modern psychology have shown us that emotion and not reason is the actuating force, and that reason is a tool in the service of the emotions. CHAPTER VIII THE SELF-PRESERVATION INSTINCT The self-preservation instinct appears to our consciousness under the guise of that deep-rooted clinging to life, that desire to live, which characterises every living thing. It is this instinct, functioning simply in simply organised creatures, that leads them to seek food and avoid danger, and also causes that complex organism, a civilised man, to carry out the elaborate activities of “earning a living.” It is essentially a selfish instinct, for it leads the individual to regard his own welfare alone, and to consider others only so far as their existence is essential to his. For instance, shooting and hunting during the breeding season are forbidden by law, not out of consideration for the hunted creatures, but because the continuation of their species is useful to us. Its influence, however, is often modified by the two other great instincts whose influence may become so strong under certain circumstances as to induce a man not only to disregard his own interests, but even to lay down his life for others.