than he could single-handed. He can not by himself answer the whole of his problem, but with the help of a corps of students, each prosecuting some particular part, he may be able to; and the students themselves gain by cooperating in such a unified project. For no one man has the ability to follow out all the clues that suggest themselves to his mind. And in the second place, a certain amount of teaching is almost necessary to prevent a man from becoming narrow, and to keep him in active touch with all sides of his subject. It is particularly important for an investigator to teach undergraduate courses, though these are the most difficult to present well, for that keeps him in touch with the broader and more generally comprehensible parts of his work. The occasional meeting with younger and fresher minds is stimulating, and clear presentation of a subject to them often clarifies our own ideas. It is probably on account of their teaching that university men are generally broader than museum curators.
Given then the opportunity to measure the different paths of knowledge, and supposing a man has made his choice congenial and has resolved to stick to it, a great step has been taken. Yet this is, after all, merely the planting of the right seed in the proper ground, much remains before the harvest. To make the simile true we should imagine that the case is one where a man is at once seed, farmer and harvest, limited and constrained by his inherited powers. We have to find our particular effective seed, to set it out with care, and to keep its nurture mainly in our hands.
The subject matter of a science can be taught us, but we have to learn to investigate mainly through our own endeavors. The teacher out of his experience can indicate a problem awaiting solution; he should be able to decide whether it be soluble, but the real work, the research, is with us. One can learn investigation only by investigation, and each man must find his own path through the maze.
Encyclopedic knowledge is often more an impediment than a help to investigation; the two are contradictory. The student may become so charged with scholastic learning that he has no room left for thinking. And as we recall the creative thinkers of the past, we find they were on the whole rather undertrained men, in consequence untired and active in thought, picking up knowledge only when it was needed. For knowledge is not an end but only a tool. Yet there still lingers the idea that during the three or four years the student devotes to his doctorate, he should try to learn the whole of his subject! University teaching, it seems to me, should be called successful only when it helps a man to independent thinking. It is wholesome to recognize our limitations, to realize that we can not carry heavy freight and at the same time make headway. The mind that has to interpret must be fresh and agile, not loaded with the thousand and one opinions of forerunners. Let us avoid burdening our strength with laborious compila-
