In a message board with some dear friends, I just wrote this:
"Fertility must not be intentionally denied, ever, in marital relations. The couple who uses contraception intentionally takes an action to deny their fertility. The couple who takes recourse to the less-fertile times has not intentionally denied fertility. The "act" which denied fertility was God's when he created a woman's menstrual cycle or menopause. Secondarily, this covers the unintentionally caused infertility which can come about as a double effect of a hysterectomy. It would be wrong to choose a hysterectomy for the primary purpose of infertility."
I have never understood intention as it relates to contraception and NFP so clearly. I praise the Lord for allowing me to have this bit of wisdom. And I can't help telling the world.