In Redemptoris Custos, Pope John Paul II taught the following:
According to Jewish custom, marriage took place in two stages: first, the legal, or true marriage was celebrated, and then, only after a certain period of time, the husband brought the wife into his own house. Thus, before he lived with Mary, Joseph was already her “husband.”
St. Thomas Aquinas joined with the unanimous teaching of the Fathers of the Church in stating that the marriage of Joseph and Mary was necessary to the Incarnation (S.T. III, q. 29, a1). Of course, St. Thomas taught that the Incarnation was necessary for our Redemption. Yet, if God ordained that the marriage was necessary for the Incarnation, then it is clear that the consent of both Joseph and Mary to the marriage was necessary for the Incarnation and therefore for our Redemption as well. It was cooperation with Jesus and through Mary. Yet, consider that the consent of Joseph, as open to any child God might send, included a commitment to carry out the role of a father as well as a husband.
Again in Redemptoris Custos:
St. Joseph was called by God to serve the person and mission of Jesus directly through the exercise of his fatherhood. It is precisely in this way that, as the Church’s Liturgy teaches, he “cooperated in the fullness of time in the great mystery of salvation” and is truly a “minister of salvation.”
Among the many obligations these roles included, one was to provide for Mary and Jesus and to do so by his labor. It was a labor that was intended to sustain Jesus until the time when He could enter public life and bring His redemptive mission to completion. By his labor for Jesus and Mary, Joseph also cooperated in our Redemption and performed an act of mercy to every human being.
We must not forget that our own labor can be offered to God as a sacrifice that can merit graces and make reparation for our own sins and the sins of others. Much labor goes to waste by not being offered to God. Brothers and Sisters, let us offer our labor and all the honest labor of the world to God in reparation for the many sins, which place an obstacle to His grace.