As a first example of the rich theological tradition a quote about the Lord’s Supper from John Calvin. He was only 27 years old at the moment he wrote this. It’s from the relative unknown Epistolae Duae, written in Basel, January 12th, 1537. You might recognize some of the important aspects of Calvin’s later teachings about the Lord’s Supper: the emphasis on the congregation’s participation, the proclamation of God’s promises as essential part of the liturgy, and indeed the symbolic signifance of bread and cup.
“Coenam esse Domini nego, ad cuius spirituales epulas, non in commune omnes qui adsunt fideles invitentur, nisi in qua et sancta panis ac calicis symbola ecclesiae proponantur, et promissiones, quibus obsignandis data est, enarrentur, et aquisita nobis per Domini mortem vitae gratia praedicitur.”
In (my own) translation: “I deny that we can talk about the Lord’s Supper, if not all believers, who are present, altogether are invited to the spiritual meal, and if not the holy symbols, bread and cup, are presented to the congregation, and if not the promises, which are given by the seals, are declared, and if not the gift of life, acquired for us by the death of the Lord, is proclaimed.”