The Catholic Church teaches that men and women should control the sex impulse just as they should control their appetite for food or drink. The principal end of marriage, as we have seen, is the purpose of its institution, the procreation and bringing up of children. The secondary end of marriage is mutual assistance and companionship, and a remedy against concupiscence. Where it is advisable, owing to the health of the mother or owing to reasons of prudence as distinct from selfishness, to limit the number of children, the Catholic Church points out that this should be done by the exercise of self-control, or by restricted use. As those who deny the possibility or even the wisdom of self-restraint are not likely to pay the slightest attention to the teaching of the Church, I will quote the opinions of two clear-thinking, non-Catholic writers. Mr. George Bernard Shaw has said: "I have no prejudices. The superstitious view of the Catholic Church is that a priest is something entirely different from an ordinary man. I know a great many Catholic priests, and they are men who have had a great deal of experience. They have at the back a Church which has had for many years to consider the giving of domestic advice to people. If you go to a Catholic priest and tell him that a life of sexual abstinence means a life of utter misery, he laughs. And obviously for a very good reason. If you go to Westminster Cathedral you will hear voices which sound extremely well, and very differently from the voices of the gentlemen who sing at music-halls, and who would not be able to sing in that way if they did not lead a life extremely different from the Catholic priest.... "I may say that I am in favour of birth control. I am in favour of it for its own sake. I do not like to see any human being absolutely the slave of what we used to call 'Nature.' Every human action ought to be controlled, and you make a step in civilisation with something which has been uncontrollable. I am therefore in favour of control for its own sake. But when you go from that to the methods of control, that is a very different thing. As Dr. Routh said, we have to find out methods which will not induce people to declare that they cannot exist without sexual intercourse." [125] Of course the use of contraceptives is the very negation of self-control. The late Sir William Osier, speaking of venereal disease, says: "Personal purity is the prophylaxis which we as physicians are especially bound to advocate. Continence may be a hard condition ... but it can be borne, and it is our duty to urge this lesson upon young and old who seek our advice on matters sexual." Section 4. THE ONLY LAWFUL METHOD OF BIRTH CONTROL