This book is called The Art of Teaching because I believe I that teaching is an art, not a science. It seems to very dangerous to apply the aims and methods of science to human beings as individuals, although a statistical principle can often be used to explain their behavior in large groups and a scientific diagnosis of their physical structure is always valuable. But a 'scientific' relationship between human beings is bound to be inadequate and perhaps distorted. Of course it is necessary for any teacher to be orderly in planning his work and precise in his dealing with facts. But that does not make his teaching 'scientific.' Teaching involves emotions, which cannot be systematically appraised end employed, and human values, which are quite outside the grasp of science. A 'scientifically' brought-up child would be a pitiable monster. A 'scientific' friendship would be as cold as a chess problem. 'Scientific' teaching, even of scientific subjects, will be inadequate as long as both teachers and pupils are human beings.