Pope Paul VI’s 1968 encyclical Humanae Vitae addresses marriage, sexuality and the regulation of births. It reiterates Catholic teaching on the procreative and unitive purposes of marital relations and, based on this, reaffirms traditional Catholic teaching against contraception.
“open wide the way for marital infidelity and a general lowering of moral standards” (source)
“Married love is also faithful and exclusive of all other, and this until death” (source)
“love is above all fully human, a compound of sense and spirit” (source)
“before, at the moment of, or after sexual intercourse, is specifically intended to prevent procreation” (source)
“one heart and one soul, and together attain their human fulfillment” (source)