The statement that oral sex is allowable in marriage as long as the activity concludes with procreative sex reflects part of the Church's teaching, but not the whole of it. On the one hand, the Church's teaching that intercourse open to procreation is the only legitimate form of complete sexual expression, even between spouses, does not imply that mutual genital stimulation other than intercourse is forbidden for spouses as part of the preliminaries to marital intercourse. But on the other hand, the activities of the spouses prior to intercourse must be moderate. Spouses are required to seek moderation and self-restraint necessary to preserve their love-making from becoming the pursuit of the shallow and apparent good of isolated sexual pleasure, rather than the authentic good of human love, sexually expressed in shared joy. There are no hard and fast rules for avoiding the immoderate pursuit of sexual pleasure, given that the life-giving and person-uniting goods of marriage are respected. Nevertheless, there are certain marks of immoderation and certain broad guidelines for marital chastity that spouses and confessors may refer to: a preoccupation with sexual pleasure, succumbing to desire in circumstances in which it would be wise to refrain, and insisting against serious reluctance of one's spouse. Pope Pius XII put it in this way: "Marriage is a mutual commitment in which each side ceases to be autonomous, in various ways and also sexually: the sexual liberty in agreement together is great; here, so long as they are not immoderate so as to become slaves of sensuality, nothing is shameful, if the complete acts - the ones involving ejaculation of the man's seed - that they engage in are true and real marriage acts." Pope Pius XII addressed these matters in his "Address to the Second World Congress on Fertility and Sterility, " May 19, 1956 (AAS, 48.473). The English translation can be found in John C. Ford, SJ, and Gerald A. Kelly, SJ, "Contemporary Moral Theology," vol. 2, "Marriage Questions" (New man Press, 1964), p. 212. In more recent times, the reasoning behind the Church's teaching on this matter is presented in Pope John Paul II's (Karol Wojtyla's) book, "Love and Responsibility" (Ignatius Press, 1993).
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