CHAPTER II
ON CONSUMMATED SINS OF IMPURITY
THESE are commonly reckoned as six in number: fornication, adultery, incest, criminal assault, rape, and sacrilege. All are grave sins against chastity, and the last five contain grave malice against other virtues as well. Something must be said about each one.
1. Fornication is the act of carnal intercourse between persons of different sex who are not married but who are free to marry.
Holy Scripture teaches us that fornication is a grave sin, for " fornicators shall not possess the kingdom of God." [1] " No fornicator hath inheritance in the kingdom of Christ and of God." [2] It is a grave sin not merely because it is forbidden by positive law, but because it is intrinsically wrong and contrary to the law of nature. Innocent XI condemned the following proposition: " It seems so clear that fornication in itself is not wrong, and is only evil because it is forbidden, that the contrary is altogether against reason." [3] This truth is sufficiently clear to unaided reason, for the human offspring requires for long years the constant care not only of the mother, but of the father as well, and so nature requires that the father should be certain, otherwise so great a burden could not be laid upon him. But the fact of paternity would be very uncertain if fornication were allowed, and so we must conclude that it is wrong in the nature of things. As St Thomas observes, [4] the fact that in particular cases the paternity of a child born out of wedlock is sufficiently clear, and the child's education can be provided for, does not militate against the force of the general argument, for in striving to lay down general rules of conduct we must have regard to what would happen ordinarily if such an action were lawful, not to what takes place in special circumstances.
2. Adultery is the act of carnal intercourse between persons of different sex of whom one at least is married to someone
