"He must be familiar with the entire pianoforte literature, must be able to illustrate at the second piano everything that he teaches, and must possess such a highly developed analytical faculty that he is able to recognize and impart the all-important "how" in distinction from the "what." The mere playing of a piece at the second piano with the remark, "I do it this way," he considered of little help to the pupil, unless the very necessary explanation of the process were also forthcoming."