Now, the timing of the act (say, if it’s engaged in during an infertile time of the month), or the particular individuals involved (say, if one or other is infertile) does not change the essential nature of the act; here the sexual act is still the same in kind, regardless of whether or not some circumstantial accidents render it infertile. As long as the act is the kind of act that could, in principle, result in procreation—even if such a result is unlikely (given the particular persons involved, or the particular temporal circumstances surrounding the act)—it still conforms to the natural ordering of the sexual act to the end of reproduction