To teach well a man needs to have a full mind. He must have discovered how to meet and have overcome the obstacles in his own path before he can be successful in teaching others how to avoid them. Bach united both qualities. Hence, as a teacher he was the most instructive, clear, and definite that has ever been. In every branch of his art he produced a band of pupils who followed in his footsteps, without, however, equalling his achievement. First of all let me show how he taught the Clavier.(173) To begin with, his pupils were made to acquire the special touch of which I have already spoken.(174) To that end for months together he made them practise nothing but simple exercises for the fingers of both hands, at the same time emphasising the need for clearness and distinctness. He kept them at these exercises for from six to twelve months, unless he found his pupils losing heart, in which case he so far met them as to write short studies which incorporated a particular exercise. Of this kind are the _Six Little Preludes for Beginners,_(175) and the _Fifteen Two-part Inventions,_(176) both of which Bach wrote during the lesson for a particular pupil and afterwards improved into beautiful and expressive compositions. Besides this finger practice, either in regular exercises or in pieces composed for the purpose, Bach introduced his pupils to the use of the various ornaments in both hands. Not until this stage was reached did Bach allow his pupils to practise his own larger works, so admirably calculated, as he knew, to develop their powers. In order to lessen their difficulty, it was his excellent habit to play over to them the pieces they were to study, with the remark, “That’s how it ought to sound.”(177) It would be difficult to exaggerate the helpfulness of this method. The pupil’s interest was roused by hearing the piece properly played. But that was not the sole result. Without the help thus given the pupil could only hope to overcome the difficulties of the piece after considerable effort, and would find it much less easy to realise a proper rendering of it. As it was, he received at once an ideal to aim at and was taught how to surmount the difficulties the piece presented. Many a young performer, still imperfect after a year’s practice, probably would master his music in a month if he once had it played over to him.