In science a definition is not a resting-place, but a stepping-stone. It is needless, therefore, to call the catalogue of obsolete and obscure definitions of happiness. Some, indeed, say that the definition, like the thing itself, is still unfound. I do not think this is so. Between the physiologists and the psychologists, I believe we are in a position to explain what happiness is; and if in parts the explanation is a trifle subtle, it is not really obscure. Happiness is not the same as pleasure, but it is generally built upon or grows out of pleasurable feelings. We must begin, therefore, our analysis with these, and with their opposites――the painful feelings. Pleasure and pain are both ultimate and undefinable experiences of the mind. We cannot resolve them further; but we can note certain unfailing relations they bear to the organism, which explain their significance. Pleasure characterizes the normal and unimpeded exercise of physiological functions of all kinds. There are as many elementary pleasures as there are sensations. Pain is present only in the reverse conditions. Modern physiologists have established, therefore, the fundamental law, that pleasure connects itself with vital energy, pain with its opposite; in which they have not gone beyond, even if they have caught up to, the maxim of Spinoza: “Pleasure is an affection whereby the mind passes to a greater perfection; pain is an affection whereby it passes to a lesser perfection.” Such is the meaning of pleasure or of pleasurable feelings; and there is no lack of writers, and weighty ones, too, who maintain that happiness is merely the excess of pleasure over pain; or the utmost pleasure we are capable of; or the aggregate of continued pleasurable feelings. All such phrases are wide of the mark. They confound distinct things, and ignore the boundaries between the different realms of mental action. We must leave the physiologists and turn to profound analysts of purely mental action, such as Hume and Kant, for the right understanding of the meaning of happiness. For these, its inseparable factors, are the Will and Self-consciousness. As Kant expresses it,――“The Desire of Happiness is the general title for all subjective motives of the Will.” Desire is really stimulated, not by the image of past pleasure, as Locke and his followers teach, but by the conception of Self. The satisfaction of desire is not merely such, but is the satisfaction of the Self, in thus reaching a greater perfection, to use Spinoza’s phrase. Only by discriminating the object from the Self can the pleasure of the subject become an end in itself. Hence the real aim of the pleasure-seeker, though he is rarely intellectually conscious of it, is to feel his own Self, his own being, more keenly. Aristotle expressed this when he wrote,――“Pleasure is the feeling which accompanies Self-realization.”