While, however, it is now widely recognized that children are entitled to sexual enlightenment, it cannot be said that this belief is widely put into practice. Many persons, who are fully persuaded that children should sooner or later be enlightened concerning the sexual sources of life, are somewhat nervously anxious as to the precise age at which this enlightenment should begin. Their latent feeling seems to be that sex is an evil, and enlightenment concerning sex also an evil, however necessary, and that the chief point is to ascertain the latest moment to which we can safely postpone this necessary evil. Such an attitude is, however, altogether wrong-headed. The child's desire for knowledge concerning the origin of himself is a perfectly natural, honest, and harmless desire, so long as it is not perverted by being thwarted. A child of four may ask questions on this matter, simply and spontaneously. As soon as the questions are put, certainly as soon as they become at all insistent, they should be answered, in the same simple and spontaneous spirit, truthfully, though according to the measure of the child's intelligence and his capacity and desire for knowledge. This period should not, and, if these indications are followed, naturally would not, in any case, be delayed beyond the sixth year. After that age even the most carefully guarded child is liable to contaminating communications from outside. Moll points out that the sexual enlightenment of girls in its various stages ought to be always a little ahead of that of boys, and as the development of girls up to the pubertal age is more precocious than that of boys, this demand is reasonable. If the elements of sexual education are to be imparted in early childhood, it is quite clear who ought to be the teacher. There should be no question that this privilege belongs by every right to the mother. Except where a child is artificially separated from his chief parent it is indeed only the mother who has any natural opportunity of receiving and responding to these questions. It is unnecessary for her to take any initiative in the matter. The inevitable awakening of the child's intelligence and the evolution of his boundless curiosity furnish her love and skill with all opportunities for guiding her child's thoughts and knowledge. Nor is it necessary for her to possess the slightest technical information at this stage. It is only essential that she should have the most absolute faith in the purity and dignity of her physical relationship to her child, and be able to speak of it with frankness and tenderness. When that essential condition is fulfilled every mother has all the knowledge that her young child needs.