St. Thomas arrives at the very center of what happened at the Last Supper, of what would happen the next day on the cross and of what happens at every subsequent Eucharist. With his own hands, Christ gives himself to us.
Our senses will be deceived by the appearance of bread and wine, which is why St. Thomas Aquinas insists that we trust only one of our senses, our hearing. On Easter, we solemnly proclaim and hear, silently sounding within our hearts, the saving news of the Gospel.
The question of trust, of giving ourselves to something outside ourselves, is quite fundamental. It goes to the nature of who we are as human beings. One might pose the question this way: Are we clams or clovers?