If we accept the principle of ascending levels of physical, emotional, mental, and spiritual functions, we should expect to find that sex makes its appearance in more than one form. We know, that is to say, that there are, not one, but many emotions and thoughts which are directly sexual, and that there would seem to be every reason why sex, which manifests variety in its physical expression, should be equally various in the realm of the mind. Further than this, we are able to advance the principle that when the emphasis is laid further away from the physical level, the functioning power on that level weakens. Man, as we have already agreed, is a more developed animal than the elephant, because he is active in thought. But he pays the price for this by the inferiority of his physical strength. Similarly, the less mentally equipped are frequently more physically powerful. Like all other rules, there are of course exceptions. But there does seem to be a principle, and a principle that we should logically expect, that the more man functions on what we have described as super-physical levels, the less powerful his strength on the physical level becomes. Again, we have seen that, morally, the physical level is the lowest. The highest human developments are those which the animal cannot reach. The ordinary physical instincts are not evil, they are simply less evolved. Some of them, like the sense of maternity, are good. But we cannot doubt that man's superiority over the animal lies precisely in his ability to do what the animal cannot do, and that, therefore, the realm of mind is "higher" than the realm of action. When the Catholic Church therefore presents religious celibacy[8] as being the higher vocation she is enunciating this very principle. She is not suggesting that non-celibacy is an evil state. We do not pretend that the profession of crossing-sweeper is evil because the profession of prime minister is a higher ambition; indeed, it would be probably disastrous to persuade a man who had a natural ability to be a crossing-sweeper to qualify as a prime minister. Relatively, a man performs his moral duty in fulfilling his vocation, for whatever grade it may be designed. The true religious celibate is the extreme exception; no one should attempt such perfection who has not the actual call. The means by which we realize our true vocation is too individual a question to enter upon here. The whole fault of the puritanic conception of sex is to assume that complete repression should be attempted by all men, and that marriage is solely a concession to failure.[9]