Origen — as excerpted in the Catena Aurea on Luke 11:9-13

“Consider then this, if the bread be not indeed the food of the soul in knowledge, without which it can not be saved, as, for example, the well planned rule of a just life. But the fish is the love of instruction, as to know the constitution of the world, and the effects of the elements, and whatever else besides wisdom treats of. Therefore God does not in the place of bread offer a stone, which the devil wished Christ to eat, nor in the place of a fish does He give a serpent, which the Ethiopians eat who are unworthy to eat fishes. Nor generally in the place of what is nourishing does he give what is not eatable and injurious, which relates to the scorpion and egg.”