We laugh, then, in infancy and adolescence, not primarily because we are “light-hearted” or “amused,” but to satisfy a natural instinct of both physiological and psychological utility. We laugh less in maturity, partly because we have not, as a rule, the same necessity of getting rid of surplus nervous energy, partly because our minds have passed the tender formative age, and partly because widening experience has developed sentiments and ideas tending to inhibit laughter. Nevertheless we do still need to a certain extent the relief which laughter brings; we feel in some degree the old hunger for it, and consequently, often at very slight provocation, we yield, and even cultivate opportunities for yielding, to the impulse which was so conspicuously operant in the years of our youth. As with every instinct, moreover, the laughing process may, and occasionally does, become perverted, as in the laughter of cynicism and contempt, and in the abnormal laughter of the overwrought—itself, however, the modern medical psychologist assures us, a medium of relief from an unbearable strain. As to the things at which we commonly laugh—the “laughable” whose nature has so perplexed philosophers—all that may safely be said is that their laugh-provoking power depends not so much on an inherent “comicality” as on the circumstances under which they occur to us, and our point of view toward them as determined by previous training and experience. Certainly, for instance, we cannot laugh at a subtle bit of wit until we have had education in the appreciation of the skilful use of language. The instincts of imitation and of sympathy, further, have a share in determining on many an occasion the functioning of the laughing instinct. Time and again we laugh merely because we see other people laughing. Personally I am inclined to think also that much at which we laugh as adults is laughable to us only by reason of subconscious association with similar occurrences which chanced to move us to laughter in our childhood. But on this point nothing positive should be asserted pending psychological investigation which has yet to be made. Conceding, however, that the laughable is and must always remain elusive, baffling, uncertain, there need be no uncertainty as to our view of laughter itself. To laugh—to laugh spontaneously and heartily—is under nearly every circumstance a good thing both for the body and for the mind. Like sleep, it refreshes; like food, it strengthens. Humanity in truth would be the poorer—and the shorter-lived—were it ever to lose this splendid heritage of the power to laugh.