9 When Elijah, in his flight from Jezebel, lay weary and desolate beneath the oak, there came an angel who raised him up and said, “Arise and eat.” And he looked, and behold there was a cake and a cruse of water at his head. Had God willed it, might He not have sent His prophet spiced wines and dainty dishes and flesh basted into tenderness? When Elisha invited the sons of the prophets to dinner, he only gave them field-herbs to eat; and when all cried out with one voice: “There is death in the pot,” the man of God did not storm at the cooks (for he was not used to very sumptuous fare), but caused meal to be brought, and casting it in, sweetened the bitter mess with spiritual strength as Moses had once sweetened the waters of Mara. Again, when men were sent to arrest the prophet, and were smitten with physical and mental blindness, that he might bring them without their own knowledge to Samaria, notice the food with which Elisha ordered them to be refreshed.
“Set bread and water,” he said, “before them, that they may eat and drink and go to their master.” And Daniel, who might have had rich food from the king's table, preferred the mower's breakfast, brought to him by Habakkuk, which must have been but country fare. He was called “a man of desires,” because he would not eat the bread of desire or drink the wine of concupiscence.
Source: Letters (New Advent)