“The breaking of the bread and the pouring or the drinking of the wine are a representation of our Lord’s broken body, His shed blood. That is the primary thing that is signified by this action and in 1 Corinthians 11 Paul specifically tells us to do this because in that way we are declaring our Lord’s death.
And, again, let me underline something we considered earlier. Do we not see here a wonderful provision made by the Lord Himself? For there have been periods in the history of the Church when the Lord’s death has scarcely been preached at all from the pulpits. It has been denied; it has been misrepresented and abused. Yes, but our Lord had given this commandment—as Paul says, ‘for I have received of the Lord that which also I delivered unto you’ (1 Cor. 11:23)—and He commanded the other apostles in the same way (Luke 22:19–20).
Though the pulpit may have failed, the Lord’s Supper has still gone on declaring, proclaiming, preaching the Lord’s death and often there has been a great incongruity, not to say contradiction, between the preaching of man and the preaching of the bread and the wine upon the communion table.”
– from Great Doctrines of the Bible, Volume 3: The Church and the Last Things by D. Martyn Lloyd-Jones