The gladness of the world grew larger to this happy girl when, towards the end of the seventh month, she was taken into the open air, and, shortly after, allowed to lie on a quilt and roll on the ground. The wooing of the passing freshness, the play of sun and shadow, the large stir of life in moving and sounding things, all this possessed her and made her “laugh and ejaculate with pleasure”. With this may be compared a note on a boy nine months old, who, lying in a clothes-basket in a garden one summer’s day, looked up at the leaves dancing in the sunshine and laughed with “a hearty noisy laugh”. The development of bodily power in this same half-year brought our little maiden much gleeful laughter. {197} Any experience of movement, passive as well as active, filled her with noisy hilarity. To ride on anybody’s foot brought out, at the end of the fifth month, the unmistakable signs of hilarious rapture. A month later, the gleeful explosion was called out by the new frolicsome experience of being jumped and tossed. Similar expressions of mirth occurred when new active movements were accomplished. In the record of the middle of the ninth month, we are told of a medley of movements, tumbling on the floor or lawn, sitting up and lying down, raising herself on the feet and hands, etc., which brought her “singular joy”. A part of the gleefulness of this widening experience of movement is due to its unexpected results. It seems probable that the first successful experiments in crawling, climbing and the rest may give rise to new complexes of muscular and other sensations which come as a joyful surprise. Such delightful surprises grow more varied and impressive when the arms and hands begin to experiment. For example, a little girl, aged two and a quarter years, happened when throwing a ball at random to jerk it over her head, and was seized with a spasm of hilarity. The gleeful outburst is apt to occur, too, later on when a child first achieves the feat—half-wonderful, half-amusing—of walking, of running and of jumping.[127] In these expanding processes of jollity or gleefulness we may detect the beginnings of more specialised forms of laughing enjoyment. Thus, in the outburst of merriment which winds up a successful attempt to climb, we recognise the germ of that mode of reaction which is apt to follow at the moment of sudden relaxation of tension on the attainment of an end. We may be sure that a child {198} of nine months finds the effort to stand a very serious and exhausting strain; and may infer that the laughter which occurs in this case is largely due to momentary relaxations of this strain.