Directly we move away from this strict doctrine to the modified popular expression of it, we find that the position is becoming more intelligible but less logical. It is consistent to regard all sex as evil. But when the average Christian, while denouncing adultery as a sin, insists on copulation in marriage as its consummation, a difficulty arises which must not be ignored. Here, in adultery, is a sin which is so serious in the eyes of Christian men, that it can never be redeemed; the stigma of impurity remains for ever on the offender. Yet this same act, if only committed under the regulation of marriage becomes not merely something permissible, but the essential act of consummation, the divine method of procreation. One can understand how an act, good in itself, can become a sin because it is performed under impermissible circumstances. But it is difficult to conceive of an act changing its integral nature, so that at one moment it is a necessary virtue, and at another the basest vice. It is, for instance, legal for a soldier to kill an enemy in battle, while it is a crime for one civilian to kill another; but the act of killing is _per se_ an evil thing, even in the case of a soldier. It never becomes so exalted as is the sex-act in marriage. The Catholic doctrine, however, while at first sight it appears to be identical with the Puritan, is actually quite distinct. For one thing there is a difference of attitude towards sin. Puritanism seems to suggest that those who have been "converted" are actually perfect. It insists that they shall keep up this outward appearance, and consequently ensures that their sins must be committed secretly. They are then sufficiently perfect to ascend, after death, direct to Heaven. Catholicism, however, is continually recognizing that man is normally a sinner; the confessional is a public recognition of this fact. Catholicism therefore approaches the question of sex with the expectation that man will sin, that the probability of his fall is so great as to make it unnecessary and undesirable to hide all traces of his sin from public view. The Puritan attitude towards sex is really that of the prude. The Catholic Church is so ready to talk about sex in a decent manner that she provides the confessional as a permanent institution. When we turn to the Catholic attitude towards sex we are faced indeed with two significant dogmas which make up a position fundamentally distinct from that of Puritanism. The first of these is the doctrine that marriage is a sacrament, and the second that the _esse_ of the marriage is the consent of the parties. The significance of the first is that marriage is not merely a licence whereby an unclean act is permitted as a sop to human weakness. The sex function, as the integral part of marriage, is acknowledged to be an actual objective of divine grace.