Pope Pius XI’s 1930 encyclical entitled Casti Connubii
acknowledged for the FIRST TIME a secondary,
unitive, purpose of intercourse.
Again 1930, very modern.
Hi iceand snow. I ended up finding what I promised so here goes:
St. Augustine recognized a unitive aspect to intercourse:
For of these certain [goods] are necessary for the sake of wisdom, as learning: certain for the sake of health, as meat and drink and sleep: certain for the sake of friendship, as marriage or sexual intercourse: for hence subsists the propagation of the human kind, wherein friendly fellowship is a great good. (Of the Good of Marriage, Section 9).
As did Gregory I:
…
when the married have intercourse with each other even incontinently, they still avoid lapse into sin, and are still saved through mercy. For they find as it were a little city, wherein to be protected from the fire; since this married life is not indeed marvellous for virtue, but yet is secure from punishment…But the married, in this course of conduct, then preserve their lives as it were in a small city, when they intercede for each other by continual supplications. Whence it is also rightly said by the Angel to the same Lot, See I have accepted your prayers concerning this thing also, that I will not overthrow the city for the which you have spoken Genesis 19:21. For in truth, when supplication is poured out to God, such married life is by no means condemned. Concerning which supplication Paul also admonishes, saying, Defraud not one the other except it be with consent for a time, that you may give yourselves to prayer 1 Corinthians 7:5. (Regula Pastoralis, Part III, Caput xxvii)
St Thomas Aquinas:
There are some who say that intercourse between married persons is not devoid of sin. But this is heretical, for the Apostle says: “Let marriage be honorable in all and the bed undefiled.”[15] Not only is it devoid of sin, but for those in the state of grace it is meritorious for eternal life. Sometimes, however, it may be a venial sin, sometimes a mortal sin. When it is had with the intention of bringing forth offspring, it is an act of virtue. When it is had with the intent of rendering mutual comfort, it is an act of justice. When it is a cause of exciting lust, although within the limits of marriage, it is a venial sin; and when it goes beyond these limits, so as to intend intercourse with another if possible, it would be a mortal sin. (Catechism of St. Thomas Aquinas, pg. 80)
I answer that, Since no act proceeding from a deliberate will is indifferent, as stated in the Second Book (Sent. ii, D, 40, 1, 3; I-II, 18, 9), the marriage act is always either sinful or meritorious in one who is in a state of grace. For if the motive for the marriage act be a virtue, whether of justice that they may render the debt, or of religion, that they may beget children for the worship of God, it is meritorious… (Summa Theologica Supplement Question 41)
Don’t fall into the trap of “it was never mentioned before, so it’s new…” mentality. Many things were never formally defined or expressed because they were simply generally accepted as common knowledge. I have no idea when the term “unitive aspect” was first used. But it doesn’t really matter in this case. It is similar to the term “transubstantiation” beign used for the first time some 1100 or 1200 years after Christianity. It’s first use did not suggest it was a new concept or teaching…there was simply a need to define an existing belief with a word that could adequately define what the long-held belief was.
And back to the OP: Contraception is grave matter for mortal sin.