In both Pope Paul VI's Humanae Vitae he states that God created sex to create children - and that man should not interfere with this system and there are priests who still argue that the rhythm method - since it involves sex for pleasure while trying to avoid kids - is therefore wrong. John Paul II's Evangelium Vitae says essentially the same thing. Some priests even consider that abstinence from sex in a marriage is apparently wrong, since married people should follow God's will to try to have children.

"Generosity. That was my first mistake."
"Experience must be our only guide; reason may mislead us."
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