Stammering, it has long been recognised, is not a malady of uniform symptomatology, like tuberculosis or typhoid fever. No two stammerers stammer precisely alike. They stumble over different letters and sounds; time, place, and circumstances have varying effects on the degree of their stammering; and the physical spasms and contortions that so often accompany this trouble differ in different stammerers. There is, too, a great variation in the onset of stammering. Mostly, it is true, it manifests itself in childhood, from the age of four to eleven. But it may not set in until much later in life; and, when it does begin in childhood, it begins under much diversity of conditions. Sometimes a child stammers almost as soon as he has learned to speak, though seldom, if ever, coincident with the learning. Often, the first appearance of stammering follows some disease like measles or diphtheria. Or, again, a child who has been speaking quite well, suddenly begins to stammer, and persists in stammering, after being brought into contact with people who are themselves stammerers. "I was entirely free of stammering," declares a clergyman, in a typical statement, "till I was five years old. At that time of life there was a gentleman who occasionally came to my father's house, and stammered very badly. I distinctly remember one afternoon trying to imitate him; when, unfortunately, he heard me, and was very indignant. So ashamed were my parents at my conduct that, after he had gone, I was taken to task and punished severely for it. Ever since that night I have been afflicted with this most distressing malady, in spite of all my efforts to overcome it." Compare a statement by a Philadelphia physician, Doctor D. Braden Kyle: "Several years ago I saw three interesting cases of stammering. Two of the cases were imitation. These two lads, who were associated with a boy several years older, the worst stammerer I ever saw, clearly imitated him. As they were constantly together, the imitation was almost continuous. They certainly developed into expert stammerers. In less than two years they were confirmed stammerers, and it was impossible for them to speak at all without stuttering and stammering."