The Mass continued: Memento, Domine and Communicantes.

With hands extended, the celebrant says:

"Memento, Domine, famulorum, famularumque tuarum N. et N. et omnium circumstantium, quorum tibi fides cognita est, et nota devotio, pro quibus tibi offerimus: vel qui tibi offerunt hoc sacrificium laudis pro se, suisque omnibus: pro redemptione animarum suarum, pro spe salutis, et incolumitis suae: tibique reddunt vota sua aeterno Deo, vivo et vero."

"Remember, O Lord, thy servants and handmaids N. and N.
and all who here around us stand, whose faith is known unto thee and their steadfastness manifest, on whose behalf we offer unto thee: or who themselves offer unto thee this sacrifice of praise, for themselves, and for all who are theirs; for the redemption of their souls, for hope of their salvation and safety; and who offer their prayers unto thee, the eternal God, the living and the true."

From this part of the canon, we learn two more teachings of the church on the mass: Holy mother church teaches us that the mass is offered for the good of the living, because it is the same as that of calvary, and Christ's sacrifice at calvary made the redemption of all those living at the time possible, as well as the dead patriarchs,prophets, and holy men who lived before Christ, and those yet to exist on earth.

Catechism of the Catholic Church:

1371 The Eucharistic sacrifice is also offered for the faithful departed who "have died in Christ but are not yet wholly purified,"¹⁹³ so that they may be able to enter into the light and peace of Christ:

The mass is offered with and for the body of Christ, the church. I have mentioned the pious custom of spiritually putting oneself beside the hosts in the ciborium. We ourselves are offered with Christ to the Father when we assist at the holy mass. The Catechism says:

1368 The Eucharist is also the sacrifice of the Church. The Church which is the Body of Christ participates in the offering of her Head. With him, she herself is offered whole and entire. She unites herself to his intercession with the Father for all men. In the Eucharist the sacrifice of Christ becomes also the sacrifice of the members of his Body. The lives of the faithful, their praise, sufferings, prayer, and work, are united with those of Christ and with his total offering, and so acquire a new value. Christ's sacrifice present on the altar makes it possible for all generations of Christians to be united with his offering.

Christ in the mass, because it is him presenting his precious blood before the Father as his perpetual intercession and mediation for us,obtains for us the needs which we implore of the father, namely, the salvation of souls, the well-being of our own souls, and the intentions we hold in our hearts for ourselves, and those who are near to us. We can come to him, the mediator of the new and eternal covenant, we can draw close to him and obtain of him the graces we need to follow him. (Hebrews 4:14-16)
The celebrant extends his hands and continues:
The church teaches that the mass is offered with all the saints in heaven:

1370 To the offering of Christ are united not only the members still here on earth, but also those already in the glory of heaven. In communion with and commemorating the Blessed Virgin Mary and all the saints, the Church offers the Eucharistic sacrifice. In the Eucharist the Church is as it were at the foot of the cross with Mary, united with the offering and intercession of Christ.
Pay attention to that bolded portion. At mass, we should envision ourselves as being at the foot of calvary itself, with Mary, St. John, and St. Mary Magdalene. Just as they were, we should not be concerned with outward participation. Outwardly, our Blessed Lady does not seem to have done much at the foot of the cross, but we know that interiorly, she was suffering all the pain of a mother seeing her son tortured to death. (Aside, September is the month of Our Lady of Sorrows.) Who would say that she, in her silence did not participate in her son's passion? Surely, she also was grieved in soul, she also felt pain, desolation, sorrow, just as Jesus experienced these feeling. Surely, John and Mary Magdalene felt the same feelings, as would anyone who saw a loved one treated so. This should be our disposition. One of quiet, reverent reflection on the mysteries of our redemption. This, is true active participation.