This policy has been so firmly established that the theory of it has never been clearly argued out. So far as it exists at all, it is a theory that walks on two feet pointing opposite ways: sex things must not be talked about because they are "dirty"; sex things must not be talked about because they are "sacred." We must leave sex things alone, they say, because God will see to it that they manifest themselves aright and work for good; we must leave sex things alone, they also say, because there is no department in life in which the activity of the Devil is so specially exhibited. The very same person may be guilty of this contradiction, when varying circumstances render it convenient. Such a confusion is, indeed, a fate liable to befall all ancient and deeply rooted _tabus_; we see it in the _tabus_ against certain animals as foods (as the Mosaic prohibition of pork); at first the animal was too sacred to eat, but in time people came to think that it is too disgusting to eat. They begin the practice for one reason, they continue it for a totally opposed reason. Reasons are such a superficial part of our lives! Thus every movement of sexual hygiene necessarily clashes against an established convention which is itself an inharmonious clash of contradictory notions. This is especially the case if sexual hygiene is introduced by way of the school. It is very widely held by many who accept the arguments so ably set forth by Frau Maria Lischnewska, that the school is not only the best way of introducing sexual hygiene, but the only possible way, since through this channel alone is it possible to employ an antidote to the evil influences of the home and the world.[186] Yet to teach children what some of their parents consider as too sacred to be taught, and others as too disgusting, and to begin this teaching at an age when the children, having already imbibed these parental notions, are old enough to be morbidly curious and prurient, is to open the way to a complicated series of social reactions which demand great skill to adjust.