The faithful have a role in the prayer of Holy Mass. Certainly it benefits to “pray the Mass” along with the priest, but it is the priest that offers the sacrifice in persona Christi by virtue of the Holy Orders. The prayer of the faithful is particularly emphasized in the new order of the Mass, thus following the Missal certainly becomes “easier” in this sense. It is not so in other rites, or in the extraordinary form. F.ex. in the Missale Romanum clearly some prayers we follow but not actively pray, like “The Lord be in my heart and on my lips that I may worthily and fittingly proclaim His Gospel” or “Accept, O Holy Father, Almighty and eternal God, this spotless host, which I, Thine unworthy servant, offer to Thee, my living and true God, to atone for my numberless sins, offenses and negligences; on behalf of all here present and likewise for all faithful Christians living and dead”.
The words of the Consecration are the words spoken by the Lord and transmitted to us by Sacred Scripture and Sacred Tradition. While the priest proclaims them, the faithful hear them and pray them in their hearts. There is a special solemnity when we echo in our hearts the words of the Consecration, but whether we do or not is truly irrelevant here in terms of the Sacrament. However, one may consider that this, and in general praying the Mass, opens our souls more to the graces of the Sacrament (which are always given in the same measure ex opere operato, but not always received in the same measure by each soul). As Bookcat stated in his two great posts above, “be attentive to the prayer and unite yourself to the Holy Sacrifice”.
