Jennings, thoroughly human in thus closing his mind to all ideas about his profession, was equally human in that he had his mind and his senses opened full width to ideas on how to make more money. If there had been money in new ideas about teaching singing Jennings would not have closed to them. But the money was all in studying and learning how better to handle the women--they were all women who came to him for instruction. His common sense warned him at the outset that the obviously easygoing teacher would not long retain his pupils. On the other hand, he saw that the really severe teacher would not retain his pupils, either. Who were these pupils? In the first place, they were all ignorant, for people who already know do not go to school to learn. They had the universal delusion that a teacher can teach. The fact is that a teacher is a well. Some wells are full, others almost dry. Some are so arranged that water cannot be got from them, others have attachments of various kinds, making the drawing of water more or less easy. But not from the best well with the latest pump attachment can one get a drink unless one does the drinking oneself. A teacher is rarely a well. The pupil must not only draw the water, but also drink it, must not only teach himself, but also learn what he teaches. Now we are all of us born thirsty for knowledge, and nearly all of us are born both capable of teaching ourselves and capable of learning what we teach, that is, of retaining and assimilating it. There is such a thing as artificially feeding the mind, just as there is such a thing as artificially feeding the body; but while everyone knows that artificial feeding of the body is a success only to a limited extent and for a brief period, everyone believes that the artificial feeding of the mind is not only the best method, but the only method. Nor does the discovery that the mind is simply the brain, is simply a part of the body, subject to the body's laws, seem materially to have lessened this fatuous delusion.