We shall not set up demands nor programmes, but simply describe the child-nature. (...) Vague and general phrases - ‘the harmonious development of all the powers and talents in the child,' and so forth - cannot provide the basis for a genuine art of education. Such an art of education can only be built up on a real knowledge of the human being. Not that these phrases are incorrect, but that at bottom they are as useless as it would be to say of a machine that all its parts must be brought harmoniously into action. To work a machine you must approach it, not with phrases and truisms, but with real and detailed knowledge.