I answer that, Two things have to be considered in this sacrament, namely, the sacrament itself, and what is contained in it. Now it was stated above (Article [1], Objection [2]) that the reality of the sacrament is the unity of the mystical body, without which there can be no salvation; for there is no entering into salvation outside the Church, just as in the time of the deluge there was none outside the Ark, which denotes the Church, according to 1 Pt. 3:20,21. And it has been said above (Question [68], Article [2]), that before receiving a sacrament, the reality of the sacrament can be had through the very desire of receiving the sacrament. Accordingly, before actual reception of this sacrament, a man can obtain salvation through the desire of receiving it, just as he can before Baptism through the desire of Baptism, as stated above (Question [68], Article [2]). Yet there is a difference in two respects. First of all, because Baptism is the beginning of the spiritual life, and the door of the sacraments; whereas the Eucharist is, as it were, the consummation of the spiritual life, and the end of all the sacraments, as was observed above (Question [63], Article [6]): for by the hallowings of all the sacraments preparation is made for receiving or consecrating the Eucharist. Consequently, the reception of Baptism is necessary for starting the spiritual life, while the receiving of the Eucharist is requisite for its consummation; by partaking not indeed actually, but in desire, as an end is possessed in desire and intention. Another difference is because by Baptism a man is ordained to the Eucharist, and therefore from the fact of children being baptized, they are destined by the Church to the Eucharist; and just as they believe through the Church's faith, so they desire the Eucharist through the Church's intention, and, as a result, receive its reality. But they are not disposed for Baptism by any previous sacrament, and consequently before receiving Baptism, in no way have they Baptism in desire; but adults alone have: consequently, they cannot have the reality of the sacrament without receiving the sacrament itself. Therefore this sacrament is not necessary for salvation in the same way as Baptism is.