Ambrose of Milan — as excerpted in the Catena Aurea on Luke 6:1-5

“Now the Jews thought this unlawful on the Sabbath, but Christ by the gift of new grace represented hereby the rest of the law, the work of grace. Wonderfully has He called it the second-first sabbath, not the first-second, because that was loosed from the law which was first, and this is made first which was ordained second. It is therefore called the second sabbath according to number, the first according to the grace of the work. For that sabbath is better where there is no penalty, than that where there is a penalty prescribed. Or this perhaps was first in the foreknowledge of wisdom, and second in the sanction of the ordinance. Now in David escaping with his companions, there was a foreshadowing of Christ in the law, who with His Apostles escaped the prince of the world. But how was it that the Observer and Defender of the law Himself both eat the bread, and gave it to those that were with Him, which no one was allowed to eat but the priests, except that He might shew by that figure that the priests’ bread was to come over to the use of the people, or that we ought to imitate the priests’ life, or that all the children of the Church are priests, for we are anointed into a holy priesthood, offering ourselves a spiritual sacrifice to God. (1 Pet. 2:5.) But if the sabbath was made for men, and the benefit of men required that a man when hungry (having been long without the fruits of the earth) should forsake the abstinence of the old fast, the law is surely not broken but fulfilled.”