East: St. Clement of Alexandria says in A.D. 191, [The Instructor of Children 2:10:91:2], "Because of its divine institution for the propagation of man, the seed is not to be vainly ejaculated, nor is it to be damaged, nor is it to be wasted."
WRH: The seed is something precious, and wasting it is a mortal sin, as we see from God's swift and just execution of Onan. Sterilization (damaging the seed) is impermissible, and so are all types of outercourse; all intercourse must be vaginal.
The saint adds [The Instructor of Children 2:10:95:3], "To have coitus other than to procreate children is to do injury to nature."
WRH: St. Clement teaches that any sexual intercourse that is not open to life is unnatural.
West: Lactantius of North Africa says in 307 [The Divine Institutes 6:23:18 in PL 6:718AB], "God gave us eyes not to see and desire pleasure, but to see acts to be performed for the needs of life; so too, the genital ['generating'] part of the body, as the name itself teaches, has been received by us for no other purpose than the generation of offspring."
East: Bishop St. Epiphanius of Salamis says in [Medicine Chest Against Heresies 26:5:2], "[certain Egyptian heretics] exercise genital acts, yet prevent the conceiving of children. Not in order to produce offspring, but to satisfy lust, are they eager for corruption."
West: Bishop St. Augustine the Hippo (Doctor of Grace) says in 388 [On the Morals of the Manicheans 18:65]:
This proves that you [Manicheans] approve of having a wife, not for the procreation of children, but for the gratification of passion. In marriage, as the marriage law declares, the man and woman come together for the procreation of children. Therefore, whoever makes the procreation of children a greater sin than copulation, forbids marriage and makes the woman not a wife but a mistress, who for some gifts presented to her is joined to the man to gratify his passion.WRH: It is a shame that some people seem to abhor unintentional pregnancy more than fornication, when children are a great blessing from God [Ps 127:3-5] and fornication is an abomination that we must avoid [Tob 4:13] in order to avoid eternal punishment [Gal 5:21].
East: Patriarch St. John Chrysostom the Great of Constantinople (Doctor & Holy Hierarch) says in 391 [Homilies on Matthew 28:5],
... in truth, all men know that they who are under the power of this disease [the sin of covetousness] are wearied even of their father's old age [wishing him to die so they can inherit]; and that which is sweet, and universally desirable, the having of children, they esteem grievous and unwelcome. Many at least with this view have even paid money to be childless, and have mutilated nature, not only killing the newborn, but even acting to prevent their beginning to live [sterilization].6th Century
West: Bishop St. Caesarius of Arles says in 522 [Sermon 1:12],
Who is he who cannot warn that no woman may take a potion so that she is unable to conceive or condemns in herself the nature which God willed to be fecund? As often as she could have conceived or given birth, of that many homicides she will be held guilty, and, unless she undergoes suitable penance, she will be damned by eternal death in Hell. If a woman does not wish to have children, let her enter into a religious agreement with her husband; for chastity is the sole sterility of a Christian woman.