Ante-Nicene Fathers, Vol VIII:
Pseudo-Clementine Literature.: Chapter XLI

Chapter XLI.—The Rainbow.

When the old man had thus spoken, Aquila answered:  “As you yourself proposed that any one who pleased should have an opportunity of answering to what you might say, my brother Niceta permits me to conduct the argument today.”  Then the old man:  “Go on, my son, as you please.”  And Aquila answered:  “You promised that you would show that there are many things in the world which have a form and species arranged by equal reason, which yet it is evident were not effected by God as their Creator.  Now, then, as you have promised, point out these things.”  Then said the old man:  “Behold, we see the bow in the heaven assume a circular shape, completed in all proportion, and have an appearance of reality, which perhaps neither mind could have constructed nor reason described; and yet it is not made by any mind.  Behold, I have set forth the whole in a word:  now answer me.”