5 But whence arose an occasion, so to say, to the Lord, to speak of this supper? One of them that sat at meat with Him (for He was at a feast, whither He had been invited), had said, “Blessed are they who eat bread in the kingdom of God.” He sighed as though after distant things, and the Bread Himself was sitting down before him. Who is the Bread of the kingdom of God, but He who says, “I am the Living Bread which came down from heaven”? Do not get your mouth ready, but your heart.
On this occasion it was that the parable of this supper was set forth. Lo, we believe in Christ, we receive Him with faith. In receiving Him we know what to think of. We receive but little, and we are nourished in heart. It is not then what is seen, but what is believed, that feeds us. Therefore we too have not sought for that outward sense; nor have we said, “Let them believe who have seen with their eyes, and handled with their hands the Lord Himself after His resurrection, if what is said be true; we do not touch Him, why should we believe?”
If we were to entertain such thoughts, we should be kept back from the supper by those “five pairs of oxen.” That ye may know, Brethren, that not the gratification of these five senses, which softens and ministers pleasure, but a kind of curiosity was denoted, He did not say, “'I have bought five pairs of oxen,' and I go to feed them;” but, “I go to prove them.” He who wishes to “prove” by “the pairs of oxen,” does not wish to be in doubt, just as St. Thomas by these “pairs” did not wish to be in doubt.
“Let me see, let me touch, let me put in my fingers.” “'Behold,' says the Lord, 'put in your fingers along My Side, and be not unbelieving.' For your sake have I been slain; at the place which you wish to touch, have I shed My Blood, that I might redeem you; and do you still doubt of Me, unless you touch Me? Behold, this too I grant; behold, this too I show you; touch, and believe; find out the place of My wound, heal the wound of your doubting.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)