And the teacher of the younger children needs this knowledge even more than the teacher of older ones. For the earlier years of the child's schooling are the most important years. It is at this time that he lays the foundation for all later learning, that he forms his habits of study and his attitude toward education, and that his life is given the bent for all its later development. Nothing can be more irrational, therefore, than to put the most untrained and inexperienced teachers in charge of the younger children. The fallacious notion that "anyone can teach little children" has borne tragic fruit in the stagnation and mediocrity of many lives whose powers were capable of great achievements. _The teacher must know the subject-matter._ The blind cannot successfully lead the blind. One whose grasp of a subject extends only to the simplest rudiments cannot teach these rudiments. He who has never himself explored a field can hardly guide others through that field; at least, progress through the field will be at the cost of great waste of time and failure to grasp the significance or beauty of what the field contains. Expressed more concretely, it is impossible to transplant arithmetic, or geography, or history, or anything else that one would teach, immediately from the textbook into the mind of the child. The subject must first come to be very fully and completely a true possession of the teacher. The successful teacher must also know vastly more of a subject than he is required to teach. For only then has he freedom; only then has he outlook and perspective; only then can he teach the _subject_, and not some particular textbook; only then can he inspire others to effort and achievement through his own mastery and interest. Enthusiasm is _caught_ and not taught. _The teacher must know the technique of instruction._ For teaching is an art, based upon scientific principles and requiring practice to secure skill. One of the greatest tasks of the teacher is to _psychologize_ the subject-matter for his pupils,--that is, so to select, organize, and present it that the child's mind naturally and easily grasps and appropriates it. Teaching, when it has become an art, which is to say, when the teacher has become an artist, is one of the most highly skilled vocations. It is as much more difficult than medicine as the human mind is more baffling than the human body; it is as much more difficult than preaching as the child is harder to comprehend and guide than the adult; it is as much more difficult than the law as life is more complex than logic.