before, at the moment of, or after sexual intercourse, is specifically intended to prevent procreation—whether as an end or as a means.16 Neither is it valid to argue, as a justification for sexual intercourse which is deliberately contraceptive, that a lesser evil is to be preferred to a greater one, or that such intercourse would merge with procreative acts of past and future to form a single entity, and so be qualified by exactly the same moral goodness as these.17 Though it is true that sometimes