Concerning the Ten Commandments, which are the Heads of the Law (16)

but even of wholesome water, in order that, when after having found themselves in want of necessary food, and expecting to be destroyed by hunger and thirst, they should on a sudden find themselves amid abundance of all necessary things, spontaneously springing up around them; the heaven itself raining down upon them food called manna, and as a seasoning delicacy to that meat an abundance of quails from the air; and the bitter water being sweetened so as to become drinkable, and the precipitous rock pouring forth springs of sweet water; then they might no longer look back upon the Nile with wonder, nor be in doubt as to whether those laws were the laws of God, having received a most manifest proof of the fact from the supplies by which they now found their scarcity relieved beyond all their previous expectations;