LAUGHTER, in physiological-psychology, an expression of emotion, consisting chiefly in certain convulsive and partly involuntary activ ities of the muscles of respiration by means of which after an inspiration the explosion of air from the lungs in a series of interruptions pro duces a succession of short abrupt movements of the muscles of the face and often of other parts of the body, along with an emission of chuckling sounds from the throat. It is•usually accompanied by a peculiar expression of the eyes, indicating merriment, keen amusement, satisfaction or derision; and even sometimes by tears. A gentle and inaudible form of laughter is called a smile. It is expressed merely in the movement of the lips and eyes. Dr. Boris Sidis discovered in the course of his investigations of the causes of laughter the primary law that °all unrestrained activities of normal functions give rise to the emotion of joy with its expres sions of smiles and laughter)); and with this as the initial point of his discussion, he begins with a consideration of the aplay-instinct° in all young animals. Upon this hypothesis Dr. Sidis builds up a tolerably convincing theory that very nearly all human activity is based upon the aplay-instinct.° Widely differing human ac tivities — church ceremonies, theatridals, out door games — contends Dr. Sidis, are at bottom things which subserve the same function. All satisfy the play-instinct. °Laughter, smiling, grinning, are all external manifestations of the play instinct)) (Dr. Sidis). In all he perceives expressions either of satisfaction, derision, con tentment or inner emotion of joy — and they all accompany the play-instinct. Thus church services and a football game become inwardly connected. From the coarse roar of an amused mob enjoying to the full the laughter induced by suffering( I), we reach, after gradation upon gradation, the inner glow of the human soul, a glow which comes to all reverent worshippers of the divine; and the ultimate, supreme manifestation of joy expressed outwardly only by a rapt expression of the countenance or by the gleam in the eye, it is yet none the less of the very essence of laughter. Laughing is the
privilege of man. It is the outburst of senti ment. Yet it is limited to the domain of rational mentality.
Homer tells us that the followers of Ulysses died with laughter at the sight of Irus writhing in anguish on the ground after Ulysses had broken his skull. Sir Thomas Urquhart is said to have died in a paroxysm of laughter, on hearing of the restoration of Charles II; a statement which is rendered sufficiently prob able by the record of similar cases anoj by the eccentric character of the individuals said so to have died. Aretmus, an ancient physician, specifies unextinguishable laughter as one of the causes of death. And other ancient writers have mentioned the names of different persons who died of excessive joy. According to the common account, even Sophocles was among this number.
John Kendrick Bangs has pointed out that the conclusion that laughter is necessarily sar donic would be a half-truth only. Yet he admits that he who endeavored to trace the causes of laughter, induced by a Broadway librettist, would find himself inevitably en meshed in a miasmatic ooze emanating from the emotional, morasses of an unspiritual bed lam. The only common element in both the mirth described by Homer and in the case just mentioned seems to him a sort of unwitting cruelty. "The highest point reached by laugh ter ,° says Dr. Sidis on the other hand, "is inti mately related to the highest intellectual, es thetic and moral development of man." These words recall the statement of Addison, that it annoyed him to see the talents of humor and ridicule in the hands of an ill-natured man. The better of our professional humorists re member this. They know that ridicule and social decadence are capable of mutual under standing, and therefore keep them apart. Pro fessional humor never forgets that to laugh with and not at people is the mission of him who would work great ends through the laughter of sympathy. They never stoop will ingly to the caustic ridicule which leaves be hind it the sting of resentment and the scar of injury and injustice. (J. K. Bangs).