Mark 6:42

It goes on: And they did all eat, and were filled: and they took up twelve baskets full of the fragments. Twelve baskets of fragments remained over and above, that each of the Apostles, carrying a basket on his shoulder, might recognise the unspeakable wonder of the miracle. For it was a proof of overflowing power not only to feed so many men, but also to leave such a superabundance of fragments. Even though Moses gave manna, yet what was given to each was measured by his necessity, and what was over and above was overrun with worms. Elias also fed the woman, but gave her just what was enough for her; but Jesus, being the Lord, makes his gifts with superabundant profusion.

(ubi sup.) Again, those men lie down on grass and are fed by the food of the Lord, who have trodden under foot their concupiscences by continence, and apply themselves diligently to hear and fulfil the words of God. The Saviour, however, does not create a new sort of food; for when He came in the flesh He preached no other things than were predicted, but showed how pregnant with mysteries of grace were the writings of the Law and the Prophets. He looks up to heaven, that He may teach us that there we must look for grace. He breaks and distributes to the disciples that they may place the bread before the multitudes, because He has opened the mysteries of prophecy to holy doctors, who are to preach them to the whole world. What is left by the crowd is taken up by the disciples, because the more sacred mysteries, which cannot be received by the foolish, are not to be passed by with negligence, but to be inquired into by the perfect. For by the twelve baskets, the Apostles and the following Doctors are typified, externally indeed despised by men, but inwardly full of healthful food. For all know that carrying baskets is a part of the work of slaves.