Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 10

Chapter 10.—Whether the Distinction Between Janus and Jupiter is a Proper One.

Since, therefore, Janus is the world, and Jupiter is the world, wherefore are Janus and Jupiter two gods, while the world is but one?  Why do they have separate temples, separate altars, different rites, dissimilar images?  If it be because the nature of beginnings is one, p. 129 and the nature of causes another, and the one has received the name of Janus, the other of Jupiter; is it then the case, that if one man has two distinct offices of authority, or two arts, two judges or two artificers are spoken of, because the nature of the offices or the arts is different?  So also with respect to one god:  if he have the power of beginnings and of causes, must he therefore be thought to be two gods, because beginnings and causes are two things?  But if they think that this is right, let them also affirm that Jupiter is as many gods as they have given him surnames, on account of many powers; for the things from which these surnames are applied to him are many and diverse.  I shall mention a few of them.