But too often they are the sick folk. Without the hardihood and the energy to conquer the outer world, they fall back on a world requiring less energy to study, less energy to conquer. Sometimes they develop a sense of unreality which vitiates all their efforts to succeed; or they become hypochondriacs, feeling every flutter of the heart and every vague ache and pain. The Hamlet doubting type is an introspectionist and oscillates in his mind from yea to nay on every question. Such as this type develop ideas of compensation and power and become cranks and fake prophets. Or else, and this we shall see again, they become imbued with a sense of inferiority, feel futile as against the red-blooded and shrink from others through pain. Everywhere one sees these phases of interest in antagonism and cooperation. The "healthy-minded" acknowledge the leadership of a past introspectionist but despise the contemporary one as futile and light-headed. The introverted (to use a Freudian term) call the others Philistines, and mock them for their lack of spiritual insight, yet in everything they do they depend for aid and sustenance upon them. Introspection gives no exact measurements of value, but it gives value and without it, there can be no wisdom. But always it needs the correction of the outer world to keep it healthy. While we have dealt here with the extremes of extrospection and introspection, it is safe to say that in the vast majority of people there is a definite and unassailable interest in both of these directions. Interest in others is not altruism and interest in the self is not self-interest or egoism. But, on the whole, they who are not interested in others never become philanthropists; they who are not interested in things never become savants; and they who do not dig deep into themselves are not philosophers. There are, therefore, certain practical aspects to the study of interest which are essential parts of the knowledge of character. 1. Is the interest of the one studied controlled by some purpose or purposes, or is it diffuse, involuntary, not well directed? 2. Is it narrow, so that it excludes the greater part of the world, or is it easily evoked by a multiplicity of things? In the breadth of interest is contained the breadth of character, but not necessarily its intensity or efficiency. There are people of narrow but intense successful interest, and others of broad, intense successful interest, but one meets, too frequently, people quickly interested in anything, but not for long or in a practical fashion. There is a certain high type of failure that has this difficulty. 3. Is its main trend outward, and if so, is there some special feature or features of the world that excite interest?