For example, to cite a few observations from the record of a lady, Miss Milicent Shinn, whose painstaking study of the infancy of her niece Ruth is among the most stimulating of contributions to the modern science of child psychology, it appears that toward the end of the fifth month this little girl “habitually laughed with glee when any one smiled or spoke to her.” And when, two months later, she was taken into the open and allowed to roll about on a quilt, “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.’” Also, like almost every child of her age, little Ruth would be moved to hilarious mirth by being given a ride on somebody’s foot, or tossed and jumped about in one’s arms. Laughter, again, followed the successful accomplishment of any intellectual or muscular feat, such as pointing out pictures she had been asked to identify, climbing stairs, or deliberately letting herself fall “so as to come down sitting with a thud.” The same tendency to excessive, even seemingly causeless laughter in the opening years of life has been noted by other close students of the emotions and their expression. Some have attempted, with the usual futile results, to explain it by an analysis of the things at which the child laughs. Others, more cautiously and more accurately, content themselves with describing it as a means whereby Nature provides a salutary outlet for surplus nervous energy. It is undoubtedly this. Ask any child who has learned to talk—or, better, ask a grown person who has retained to a marked degree the faculty for hearty laughter—and the chances are you will be told that, while in any given instance the laugher may be far from clear as to why he has laughed, he does know that the involuntary movements of the laughter to which he yielded were preceded by peculiarly compelling sensations, variously expressed in such phrases as, “I had to laugh or burst,” “I had to do something to relieve the strain,” “I felt bubbling over,” “I felt a quiver, a thrill, a creepy feeling passing from my stomach to my mouth.”