What all of us need is a reference to Grace 101. As Aquinas notes, the sacraments were not necessary before the Fall, but after the Original Sin, man needed physical signs of spiritual life. The sacraments of Christ, as found in the New Testament, produce grace. As the Great Doctor notes, we are only incorporated into Christ through grace, and grace is given through the sacraments.
The sacraments are the instrumental cause of grace, God being the principal cause. Because the sacraments, (and this is all in Thomas), are the instruments of grace, these sacramental graces are actually brought to fruition through the instrument of the sacrament.
The essence of the soul is perfected by the grace of the sacraments. Now, in order to receive grace, one cannot be in mortal sin. Mortal sin stops the flow of grace, the soul being unable to receive new graces until the sin is removed, absolved in the sacrament of Penance.
There is a particular grace from each sacrament. Therefore, there is a sacramental grace of and for marriage, of and for the priesthood, and of and for the reception of the Eucharist.
Each sacrament has an end. And, the corresponding grace for that sacrament, states Thomas, moves a person towards that end. Hence, the sacramental grace of marriage leads a couple towards a happy and complete marriage in Christ.
The powers of the soul are affected by the grace of the particular sacrament. We are truly absolved of sin through the sacrament of Confession, or Penance, or Reconciliation, however it is labelled.
We are truly made one as a couple in Christ, if we truly receive the sacrament of marriage.
If we receive the Body and Blood of Christ, we are transformed into His Passion and Death, becoming one with Him through the grace of unity. The Eucharist, if taken in piety and in grace, is the consummation of baptism, bringing about the perfection of the person through the grace of union with Christ.
The messy ideas floating around the Synod seem to be a set of ideas which ignore some basic tenets of the Faith.
1) In order to receive graces in the sacraments of marriage and Eucharist, one must be in grace.
2) Grace builds upon grace, and the sanctifying grace of the sacraments cause an effect. allowing other graces to become stronger, even habits of virtue. Without that initial reception of grace, nothing happens.
3) Each sacrament gives a particular grace as well as sanctifying grace. Eucharist does not give absolution for mortal sin, does not forgive sin, under usual circumstances. Reconciliation does this. Marriage does not bring about a grace of celibacy. Ordination gives this grace. Ordination does not give a grace for raising children or discerning the children's vocation. Marriage gives a particular grace for faithfulness and long-suffering in an intimate relationship. The Eucharist was not given to us to take away mortal sin, but to nourish us, give us more grace, unite us with God, and cure our infirmities, states Thomas. To deny that each sacrament has a purpose and a particular grace seems like basic theology of sacramental grace. Perhaps some have forgotten this at the Synod....or want to deny it.
4) Without the reception of a specific sacrament, grace is absent. Therefore, only natural graces inform couples who are not married regularly, not supernatural graces. And so on...particular graces are not the same as inclusive sanctifying grace.
5) The disposition of the person is important in Catholic sacramental theology. Grace follows grace. This doctrine separates us from the Lutherans and other Protestants, who see grace as purely an individual relationship with God, outside of a church, and totally "private". Sola gratia is actually clarified in Trent, meaning that the deeds or works of men have nothing to do with meriting grace. But, that is it sheer gift, to those already in grace. Disposition means that one is in sanctifying grace, in good standing with Holy Mother Church and able to receive the grace of the sacraments.
Justification prepares us for sanctifying grace and this justification involves the forgiveness of sins, (absolution from the sacrament of Reconciliation), and the dedication to following a life of holiness, or metanoia.
The inner reality of sanctifying grace changes a person spiritually, and even physically. This grace is a supernatural quality of the soul. One can see that those who want to allow those in mortal sin to be able to receive the Lord's Body and Blood in the Eucharist simply do not understand, or want to hold, this basic teaching of the Church regarding grace. Grace gives us the disposition to act in a holy manner, to practice virtue.