He sure did. He reminds the reader what Augustine taught about sex: that it should be practiced because of it’s use (and we all know what is use of sex for Augustine), not for enjoyment (ie. anything else).
The chapter is called “The Sanctity of the Marriage Bed”, meaning he talks about sex, not videogames.
I am aware of that.

But the quote from St. Augustine is speaking of worldly things in general. The same attitude must be taken even in the context that St. Francis quotes him in. The division between using a worldly thing (intercourse included) and enjoying it (if you mean the basic meaning) is not strict. I think what Augustine had in mind with “enjoy” was excessive attachment.
Condition such as pregnancy or sterility will not make the act evil. Even having sex on infertile day of the cycle is not bad.But when this condition is used specifically to avoid procreation (for example, if man marries sterile woman so he could have sex without children) it is problematic. Same goes with NFP. To have sex on infertile day because it is infertile, is not accidental- thus, not acceptable.
Whoever St. Francis de Sales is addressing probably knows that during pregnancy a woman cannot procreate. At least, we know for certain that St. Francis knew this. If they didn’t know that pregnancy was a time when one could not conceive, then they surely found out when the read St. Francis’ work. And if they knew this fact, perhaps they were not using the pregnancy period as a means to avoid conception,
per se, (they’d have to have gotten pregnant very often) but they are having relations knowing that procreation will not result. According to your interpretation of St. Augustine, that would be a venial sin, and according to your interpretation of St. Clement, “wasting the seed”. And according to your interpretation of St. Francis himself, they would be
enjoying intercourse, but not
using it for purposes of procreation (clearly they can’t be because they know the woman is not able to conceive at the time). If that were indeed correct, St. Francis would be contradicting himself in the same chapter. But instead he says that it’s not a sin even when the couple knows they won’t conceive (clearly a pregnant or sterile woman knows she will not) provided that they have intercourse in a way that would result in conception if it weren’t for the sterility or the pregnancy.
Same as St. Augustine. Nobody ever claimed that the belief sex is only for procreation would forbid barren or pregnant couples to have intercourse.
That is exactly what you have been claiming. If sex is solely for procreation, as you said St. Augustine said very clearly earlier in the thread, then barren and pregnant couples could NOT have sex without sinning. For what purpose would they be doing it?

They can’t be doing it with a procreative intent because they cannot procreate (at least at the time). Of course, St. Thomas and St. Francis argue that there are other reasons for intercourse and therefore having relations even at times when one knows one is infertile is not sinful.
Let’s go further with Thomastic thought. By it’s “essence”, woman is “fertile” as some accident has to happen for her to become “infertile”. Yet, woman in infertile period of the menstrual cycle is not in essence infertile- since she theoretically can conceive.
I think we should agree on our object. I was speaking of act itself previously, but you now speak of woman. Woman is a substance. In this case, fertility and infertility are accidents. They are not essential to the woman. Obviously she would still be a woman whether she were fertile or infertile. Hence, St. Thomas argues that a man who has intercourse with a woman even though she is sterile is not sinful, since it is only accidentally so as oppose to essentially like in the “sin against nature”.
This is common sense. A woman is not considered “barren” while in infertile period.
She certainly can be, in so far as she cannot conceive at that time.
Since cycle is not accident, but something of the woman’s essence, you can’t tag infertile period as accident. It would be like saying sleeping is an accident to being awake.
Sleeping and being awake are both accidents. If one of them were essential, the other could not happen because it would be
essential to a person. The person would cease to be themselves if they were awake or a sleep. That is not the case with fertility or infertility. If fertility were essential, then a woman would always have to be fertile to be a woman. Therefore, they are both accidental (nonessential).
They surely can not. They are not accidents.
However, if you are having sex on infertile day by accident, it is not sinful. If you chart, such sexual act is not an accident- it is planned in advance with desire to ejaculate semen without chance of providing generation.
What has to be understood is that when St. Thomas uses the phrase “by accident” he is not talking about a mistake. He is talking about nonessential properties i.e. fertility. St. Francis de Sales rightly considers pregnancy and sterility (and I think it’s property to consider infertile periods as such also) as accidental conditions because a woman would still be a woman even without them.