Is it not true that we understand the “nature” of man to be embedded in the meaning of person,? And is it not true that we understand the meaning of created human person to be taken from Genesis 1, 26 as image and likeness of the divine Persons? And do we not understand the presence of divine Person to be enfleshed and one of us as the divine/human Jesus Christ [as in GS #22]? And would it not be true that, as the divine Persons are pure and total Relations to each Other and in Themselves, that we would have to understand their “nature” as intrinsically (constitutively) relational. And do we not understand relationality in this sense as “gift of self” as conceptualized in Gaudium et Spes #24 (since the text itself of GS 24 of “self-gift” is the way the Magisterium translated the meaning of Trinitarian relation)? And also, is it not true that the Magisterium in GS #48-went through a “development” from the scholastic understanding of matrimony as a contract of two individuals-objects [male and female] of a rational nature who unite in conjugal union for the primary purpose of procreation, now understands matrimony as a covenant of male and female persons-subjects for the purpose of becoming one flesh and “open” to procreation.
And so, clearly, when we speak of “natural law” as the rule to which we should hew when speaking of matrimony, would it not be more correct and clear to speak of “the law of the person” meaning by that: the spouses must master themselves as subjects, possess themselves as persons in order to give themselves as persons, as “I’s”.
In the light of this, it must be noted that Humanae Vitae did not couch its argument in eminently personalist, subjective terms, but more as an objective document about the morality of the conjugal act. George Weigel wrote that as HV proposed the act as it defining center, The Krakow commission memorandum (formed by Wojtyla) proposed the human person, not the human act, as the starting point. The Krakow theologians argued that the Creator had inscribed what might be called a moral language and grammar in the sexual structure of the human body which is the very person himself. Weigel’s point quoting Fr. Bardecki was that HV did not adopt in full the rich personalist context suggest by the Krakow commission. Absent this context, with its emphasis on human dignity and on the equality of spouses in leading sexually responsible lives, opened HV to the charge of legalism, ‘biologism,’ and pastoral insensitivity. It left the Church vulnerable to the accusation that it had still not freed it self of the shadowof Manichaeism and its depreciation of sexuality. That is, HV had not provided an adequately personalist framework in which to engage its teaching. I suggest, if you can make time, read the Krakow report.
 “Indeed the Lord Jesus, when He prayed to the Father ’that all may be one… as we are one (Jn. 17. 21-22)… implied a certain likeness between the union of the divine Persons and the unity of God’s sons in truth and charity.”
 G. Weigel, “Witness to Hope” Cliff Street Books, (1999) 207-210.