One may, perhaps, go farther and say that the series of gradations here indicated is gone through, more or less rapidly, in an ordinary laugh. Persons who laugh slowly, finding it difficult to “let themselves go,” can be seen to pass through these stages. It has been said by an ingenious American inquirer that laughter may begin either with the eyes or with the mouth, the frequency of the former mode, as compared with the latter, in the instances examined being as 7 to 5.[14]
It may be added that, to this continuity of form in the actions of smiling and laughing, there answers a community of function. As will be shown more fully by-and-by, both are in their primitive forms manifestations of pleasure, laughter being primarily the expression of the fuller measures of the happy or gladsome state, and varying in energy and volume with the degree of this fulness.
The chronological relations of the reign of the smile and the laugh in the life of the individual will occupy us {29} presently. Here it may be enough to say that these relations allow us to think of smiling at once as the precursor and as the successor of her kinsman. The first smiles are a step away from the exceeding gravity of baby-hood towards full hilarity, the last are a step back from this hilarity to the stolid composure of senile infancy.
It would seem to follow that the sharp distinction often drawn between smiling and laughing is artificial. Society, led by its Chesterfield, may emphasise the difference between the incipient and the completed process, allowing the one and forbidding the other; but the natural man is inclined to regard them as one.
The recognition of this identity of the two actions is evidenced by the usages of speech. We see in the classical languages a tendency to employ the same word for the two, laughing like smiling being regarded—primarily and mainly at least—as an object of visual perception. This is particularly dear in the case of the Latin “ridere,” which means to smile as well as to laugh, the form “subridere” being rare. This tendency to assimilate the laugh and the smile as facial expressions was naturally supplemented by the employment, both in Greek and in Latin, of a separate word for audible laughter (“καχάζειν”, “cachinnare”) in cases where it was needful to emphasise the fact of sound. In some modern languages the relation of smiling to laughing is precisely indicated as that of a less full to a fuller action (Italian, “ridere” and “sorridere”; French, “rire” and “sourire”; German, “lachen” and “lächeln”). Possibly the existence of two unrelated words in our own and some other modern languages points to the fact that certain races have been more impressed by the dissimilarity between the audible and the inaudible expression than by the similarity of the visible manifestations. {30}
It is worth noting that even after the two expressions have been distinguished by separate names there is a tendency to use the stronger metaphor “to laugh,” rather than the weaker one “to smile,” in describing the brighter aspects of nature’s beauty, such as meadows when in flower. A painter, whom Dante meets in Purgatory, and recognises as the first in the art of illumination, gracefully transfers this distinction to a brother painter by saying that the leaves which the latter painted “laugh more” (piu ridon) than his own.[15]
We may now turn to the distinguishing characteristics of laughing, that is, the production of the familiar series of sounds. Like sighing, sobbing and some other actions, it is an interruption of the natural rhythm of the respiratory process, in which inspiration and expiration follow one another at regular intervals. The obvious feature of this interruption in the case of laughter is the series of short, spasmodic, expiratory movements by which the sounds are produced. These are, however, preceded by a less noticed inspiration of exceptional energy and depth. These interruptions of the ordinary respiratory movements involve an unusually energetic action of the large muscles by which the chest is expanded, viz., those which secure the contraction and so the descent of the dome-shaped diaphragm, and those by the action of which the ribs are elevated.
The production of the sounds by the spasmodic expiratory movements shows that the passage from the trachea into the pharynx, viz., the glottis or chink between the vocal cords, is partially closed. The quality of the sounds is {31} explained by the particular arrangements, at the moment of the cachinnation, of the vocal apparatus, and more particularly the shape of the resonance chamber of the mouth.
Familiar though we are with them, we should find it hard to give an accurate description of the sounds of laughter. To begin with, they seem to vary considerably in the case of the same person and still more in that of different persons. Laughter has not yet lent itself to the methods of the experimental psychologist, and so has not been studied with scientific precision. By-and-by, we may hope, the phonograph will capture its sounds, and enable us to observe them at our leisure. Meanwhile, only a very rough account of them is possible.
Taking the laughter of the adult male, which is perhaps more frank and better pronounced, we find the more common forms of iterated sounds to range from the broad vowel sound aw (in “law”) to the sharp a (in “bat”). The long o sound (as in “go”), involving the rounded mouth aperture, seems to me to be far less common. The same applies to the long ee and ai sounds, and those which seem to be most closely allied to them.