my reply in read:
Clearly if the majority of Church Fathers taught that it was sinful to have marital relations when no longer fertile,
No one has shown any authority teaching that the majority of Church Fathers taught that it was sinful to have marital relations when no longer fertile. This subject shift is a poor distraction. Take it to another thread, in the Ridiculous Comments Section.
Pius XI Infallible declared CLEARLY in Casti Connubi:
…"No reason, however grave, may be put forward by anything intrinsically against nature may become conformable to nature and morally good. Since, therefore, the conjugal act is destined primarily by nature for the begetting of children, those who in exercising it deliberately frustrate its natural power and purpose, sin against nature, and commit a deed which is shameful and intrinsically vicious … any use whatsoever of matrimony exercised in such a way that the act is deliberately frustrated in its natural power to generate life is an offense against the law of God".
The thing is, bowler, engaging in the marital act between periods of ovulation is not frustrating anything, nor does it go against nature.
That's true, however, you overlooked "deliberately frustrated [/u]in its natural power to generate life is an offense against the law of God".
The thing is, Mithrandylan, that deliberately engaging in the marital act only between periods of ovulation is frustrating the generation life , and does go against nature. Specially when it is 99.99% accurate.
The precision of Pius XI infallible decree leaves no room wiggle room.
Frustrate: "to prevent (efforts, plans, etc.) from succeeding : to keep (someone) from doing something (Merriam-Webster)."
Nothing is being prevented from happening when a couple has relations between ovulation because nothing can happen in the first place. (you are in denial. They ARE deliberately avoiding the fertile periods!!!)
If a couple uses NFP habitually because they don't want to conceive and don't have a grave reason, that is a sin against marriage, and IMO usually a mortal sin because they are abusing marriage.
But that is NOT what Pius XII taught. That is what the NewChurch teaches. Pius XII taught that for a grave reason, couples may practice NFP. He did not say they must, or that they ought to, but that they may. And that is because even without a reasonable chance to conceive, sɛҳuąƖ relations have a secondary end in satisfying concupiscence. See my previous post in response to Director for more on this. (Pius XI's teaching is infallible and it is clear. Pius XII's teaching is a fallible opinion expressed to some midwives convention and is opposed to Pius XI's infallible teaching. This is a matter of reading clear language on both sides.)
OK, so are they avoiding or frustrating? Pius XI teaches that it is a grave sin against the natural order to deliberately frustrate it's natural power or purpose. He does not say it is a grave sin against nature to deliberately avoid it's natural power or purpose. Obviously you can see the error in contending this. If it was a grave sin (against nature, no less) then not only would clergy be bound to engage in the marital act, it would contradict scripture and the fathers, which teach that the virgin state is a higher calling than the married state.
Marrying and then never having sex during fertile times indefinitely to avoid having children without grave reason is a sin against marriage, because the primary purpose of marriage is the procreation and rearing of children. To enter into that state without an intention of having children actually invalidates the marriage (which means that the couple are fornicating); and to marry and indefinitely and deliberately and "put off" having children (without grave reason) is a mortal sin against marriage because it is a failure to fulfill your duty of state as well as a breach of the contract, a contract that has the primary end of generating and rearing children.
But it is not a sin against nature. It is key for you to understand this. It may be
contraceptive, but it is not the act of contraception. Whether done in a sinful or licit manner, having sɛҳuąƖ relations when a woman is not ovulating does not frustrate the natural power to conceive, because the natural power to conceive
does not exist at that time.
There is nothing to frustrate. Pius XII actually says all of this in his address to the midwives:
If the application of that theory [NFP] implies that husband and wife may use their matrimonial right even during the days of natural sterility no objection can be made. In this case they do not hinder or jeopardize in any way the consummation of the natural act and its ulterior natural consequences. It is exactly in this that the application of the theory, of which We are speaking, differs essentially from the abuse already mentioned, which consists in the perversion of the act itself. If, instead, husband and wife go further, that is, limiting the conjugal act exclusively to those periods, then their conduct must be examined more closely.
Here again we are faced with two hypotheses. If, one of the parties contracted marriage with the intention of limiting the matrimonial right itself to the periods of sterility, and not only its use, in such a manner that during the other days the other party would not even have the right to ask for the debt, than this would imply an essential defect in the marriage consent, which would result in the marriage being invalid, because the right deriving from the marriage contract is a permanent, uninterrupted and continuous right of husband and wife with respect to each other.
However if the limitation of the act to the periods of natural sterility does not refer to the right itself but only to the use of the right, the validity of the marriage does not come up for discussion. Nonetheless, the moral lawfulness of such conduct of husband and wife should be affirmed or denied according as their intention to observe constantly those periods is or is not based on sufficiently morally sure motives. The mere fact that husband and wife do not offend the nature of the act and are even ready to accept and bring up the child, who, notwithstanding their precautions, might be born, would not be itself sufficient to guarantee the rectitude of their intention and the unobjectionable morality of their motives.
...
Serious motives, such as those which not rarely arise from medical, eugenic, economic and social so-called "indications," may exempt husband and wife from the obligatory, positive debt for a long period or even for the entire period of matrimonial life. From this it follows that the observance of the natural sterile periods may be lawful, from the moral viewpoint: and it is lawful in the conditions mentioned. If, however, according to a reasonable and equitable judgment, there are no such grave reasons either personal or deriving from exterior circuмstances, the will to avoid the fecundity of their union, while continuing to satisfy to the full their sensuality, can only be the result of a false appreciation of life and of motives foreign to sound ethical principles.
Pius XII teaches:
1) Birth control is wrong (not quote in this passage, but occurs earlier in the letter)
2) By itself, sɛҳuąƖ relations during natural sterility are not wrong
2.1) The morality of such relations is determined by the intentions of the couple
2.2) Even if determined to have immoral intentions, it is not the same
sin as b/c.
3) Delegating relations to sterile periods may be lawful if the requisite conditions are met.
What more do you want? He clearly doesn't teach what you are saying he does, or if he does, you are wrong and shamefully prideful for rejecting it, as it does not at all conflict with Pius XI.