Sexual curiosity normally begins during the third year, in the shape of an interest in the physical differences between men and women, and between adults and children. By nature, this curiosity has no special quality in early childhood, but is simply a part of general curiosity. The special quality which it is found to have in children who are being conventionally brought up is due to the grown-up practice of making mysteries. When there is no mystery, the curiosity dies down as soon as it is satisfied. A child should, from the first, be allowed to see his parents and brothers and sisters without their clothes whenever it so happens naturally. No fuss should be made either way; he should simply not know that people have feelings about nudity. (Of course, later on he will have to know.) It will be found that the child presently notices the differences between his father and mother, and connects them with the differences between brothers and sisters. But as soon as the subject has been explored to this extent, it becomes uninteresting, like a cupboard that is often open. Of course, any questions the child may ask during this period must be answered just as questions on other topics would be answered. Answering questions is a major part of sex education. Two rules cover the ground. First, always give a truthful answer to a question; secondly, regard sex knowledge as exactly like any other knowledge. If the child asks you an intelligent question about the sun or the moon or the clouds, or about motor-cars or steam-engines, you are pleased, and you tell him as much as he can take in. This answering of questions is a very large part of early education. But if he asks you a question connected with sex, you will be tempted to say, “hush, hush”. If you have learnt not to do that, you will still answer briefly and dryly, perhaps with a trifle of embarrassment in your manner. The child at once notices the _nuance_, and you have laid the foundations of prurience. You must answer with just the same fulness and naturalness as if the question had been about something else. Do not allow yourself to feel, even unconsciously, that there is something horrid and dirty about sex. If you do, your feeling will communicate itself to him. He will think, necessarily, that there is something nasty in the relations of his parents; later on, he will conclude that they think ill of the behaviour which led to his existence. Such feelings in youth make happy instinctive emotions almost impossible, not only in youth, but in adult life also.