Happiness is conjunctive with an increase in vitality, intensity of feeling and thinking, and productiveness; unhappiness is conjunctive with the decrease of these capacities and functions. Happiness and unhappiness are so much a state of our total personality that bodily reactions are frequently more expressive of them than our conscious feeling. (…) Indeed, our body is less capable of being deceived about the state of happiness than our mind (…). The subjective feeling of being happy, when it is not a quality of the state of well-being of the whole person, is nothing more than an illusory thought about a feeling and is completely unrelated to genuine happiness. Pleasure or happiness which exists only in a person’s head but is not a condition of his personality I propose to call pseudo-pleasure or pseudo-happiness. ― (1947a: Man for Himself. An Inquiry into the Psychology of Ethics, New York (Rinehart and Co.) 1947, pp. 181f.)
Happiness is an achievement brought about by man’s inner productiveness and not a gift of the gods. Happiness and joy are not the satisfaction of a need springing from a physiological or a psychological lack; they are not the relief from tension but the accompaniment of all productive activity, in thought, feeling, and action. Joy and happiness are not different in quality; they are different only inasmuch as joy refers to a single act while happiness may be said to be a continuous or integrated experience of joy; we can speak of „joys“ (in the plural) but only of „happiness“ (in the singular).
Happiness is the indication that man has found the answer to the problem of human existence: the productive realization of his potentialities and thus, simultaneously, being one with the world and preserving the integrity of his self. In spending his energy productively he increases his powers, he „burns without being consumed.“ (Ex 3:2) ― (1947a: Man for Himself. An Inquiry into the Psychology of Ethics, New York (Rinehart and Co.) 1947, p. 189.)