81 Perhaps they brought him flesh in the evening, as it were stronger food, such as the Corinthians, whose minds were weak, could not take, and were therefore fed by the Apostle with milk. So, stronger meat was brought in the evening of the world, in the morning bread. And so, because the Lord commanded this food to be supplied, that word of prophecy may be suitably addressed to Him in this place: “You will give joy in the outgoings of morning and evening;” and, farther on: “You have prepared their food, for so is its preparation.”
Source: Letters (New Advent)