Here is my explanation, a few pages in. The thread is now over 40 pages, and likely to get longer--the arguments have mostly been small blow for blow things, rather than lengthy discourses, so it's moving quickly.
Perhaps an analogy would be helpful. Let us say that we have put a lamp in a house with many windows. As we pass by the windows, we see the light. As we pass by the walls, we do not see the light, but it is continually burning. Therefore, we do not relight the lamp each time we pass by a window; the lamp is burning independently of our passing by.
To translate: the Sacrifice of Calvary is the lamp, it is an eternal, timeless reality. When we attend the Holy Mass, we are passing by a window to Calvary--that is, the light of Christ's sacrifice shines down through the ages and is made present every time the Mass is said. No matter how many windows we pass by, there is still one light continually shining, just as every Mass is truly one sharing in that continually merit-bearing sacrifice.
Admittedly, this analogy is imperfect, as Christ's sacrifice on the Cross does not just bear us merit when we attend Mass--indeed, it touches every part of our lives. But it is when we are at Mass that we are placed at the foot of the Cross. As Archbishop Fulton Sheen of blessed memory said in the introduction to the book "This Is the Mass:"
|If the Blessed Mother and St. John at the foot of the Cross had closed their eyes when Our Lord was offering himself for the sins of the world, the spiritual effects on them would have been no different from those which we may receive as we assist at the Sacrifice of the Mass. But if their eyes were open, there would have been this difference: they would have seen the sacrifice offered in bloodshed with blood pouring from gaping holes in hands and feet and side. In the Mass, we see it performed without bloodshed.|