Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 28

Chapter 28.—64.  Petilianus said:  "But yet, if I may be allowed the comparison, it is certain that the sun appears double to the insane, although it only be that a dark blue cloud often meets it, and its discolored surface, being struck by the brightness, while the rays of the sun are reflected from it, seems to send forth as it were rays of its own.  So in the same way in the faith of baptism, it is one thing to seek for reflections, another to recognize the truth."

65.  Augustin answered:  What are you saying, if I may ask?  When a dark blue cloud reflects the rays of the sun with which it is struck, is it only to the insane, and not to all who look on it, that there appear to be two suns?  But when it appears so to the insane as such, it appears to them alone.  But if I may say so without being troublesome, I would have you take care lest saying such things and talking in such a way should be itself a sign of madness.  I suppose, however, that what you meant to say was this,—that the just had the truth of baptism, the unjust only its reflection.  And if this be so, I venture to say that the reflection was found in that man of our party, 2060 to whom not God, but a certain Count, 2061 was God; but that the truth was either in you or in him who uttered the witty saying against Optatus, when he said that "in the Count he had a god for his companion." 2062   And distinguish between those who were baptized by either of these, and in the one party approve the true baptism, in the others exclude the reflection, and introduce the truth.

Footnotes

Optatus.

Gildo.

See above, on 23, 53.