The Holy Supper was instituted by the Lord so that through it the church would be joined to heaven and to himself. Therefore it is the holiest form of worship.
However, people who do not know anything about the inner or spiritual meaning of the Word do not grasp how the Holy Supper accomplishes this joining together, because their thoughts do not go beyond the Word’s outward meaning, which is its literal meaning. It is from the Word’s inner or spiritual meaning that we know what is meant by the body and the blood, the bread and the wine, and eating.
In the spiritual meaning, the Lord’s body or flesh, like the bread, is the goodness of love, and the Lord’s blood, like the wine, is the goodness of faith, while eating is our making these kinds of goodness our own and becoming joined to the Lord by them. This is how the angels who are with us when we are taking the Holy Supper understand it, because they perceive everything spiritually. Therefore holy love and holy faith flow into us from the angels—that is, through heaven from the Lord—at that time, and this brings about the partnership.
We can see from this that when we take the bread, which is the body, we are joined to the Lord through the goodness of love for him that comes from him; and that when we take the wine, which is the blood, we are joined to the Lord through the goodness of faith in him that comes from him.
It is important to know, however, that this being joined to the Lord through the sacrament of the Supper occurs only for people who are devoted to the goodness of love for the Lord and faith in the Lord that come from the Lord. For such people this joining together takes place through the Holy Supper; for others there is no joining together, but the Lord is nonetheless present with them.
Furthermore, the Holy Supper includes and encompasses all the worship of God instituted in the Israelite church. In fact, the burnt offerings and sacrifices that were central to the worship of that church were collectively referred to as “bread.” The Holy Supper, then, also serves as the culmination of all those practices.
from New Jerusalem, Sections 210-214