"This is ... My Body" (Matthew 26:26): A study in the use of Metaphor

The word “resembles” marks a simile, “represents” is the word that marks a metaphor. We have recourse to metaphor when we say of a photograph, “This is my father,” or “This is my mother.” The verb “is” means, in this case, represents. The verb “is” always has this meaning, and no other, when used as a metaphor. So … what did Christ mean when He said “This is my body”? To what was He alluding? What was He meaning?