Ambrose of Milan
Catena Aurea · Lukasevangelium 6
And it came to pass on the second sabbath after the first, that he went through the corn fields; and his disciples plucked the ears of corn, and did eat, rubbing them in their hands. And certain of the Pharisees said unto them, Why do ye that which is not lawful to do on the sabbath days? And Jesus answering them said, Have ye not read so much as this, what David did, when himself was an hungred, and they which were with him; How he went into the house of God, and did take and eat the shewbread, and gave also to them that were with him; which it is not lawful to eat but for the Priests alone? And he said unto them, That the Son of man is Lord also of the sabbath.
But herein is a great mystery. For the field is the whole world, the corn is the abundant harvest of the saints in the seed of the human race, the ears of corn are the fruits of the Church, which the Apostles shaking off by their works fed upon, nourishing themselves with our increase, and by their mighty miracles, as it were out of the bodily husks, plucking forth the fruits of the mind to the light of faith.