Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 14

Chapter 14.—Concerning the Offices of Mercury and Mars.

But they have not found how to refer Mercury and Mars to any parts of the world, and to the works of God which are in the elements; and therefore they have set them at least over human works, making them assistants in speaking and in carrying on wars.  Now Mercury, if he has also the power of the speech of the gods, rules also over the king of the gods himself, if Jupiter, as he receives from him the faculty of speech, also speaks according as it is his pleasure to permit him—which surely is absurd; but if it is only the power over human speech which is held to be attributed to him, then we say it is incredible that Jupiter should have condescended to give the pap not only to children, but also to beasts—from which he has been surnamed Ruminus—and yet should have been unwilling that the care of our speech, by which we excel the beasts, should pertain to him.  And thus speech itself both belongs to Jupiter, and is Mercury.  But if speech itself is said to be Mercury, as those things which are said concerning him by way of interpretation show it to be;—for he is said to have been called Mercury, that is, he who runs between, 276 because speech runs between men:  they say also that the Greeks call him ῾Ερμῆς, because speech, or interpretation, which certainly belongs to speech, is called by them ἑρμηνεία:  also he is said to preside over payments, because speech passes between sellers and buyers:  the wings, too, which he has on his head and on his feet, they say mean that speech passes winged through the air:  he is also said to have been called the messenger, 277 because by means of speech all our thoughts are expressed; 278 —if, therefore, speech itself is Mercury, then, even by their own confession, he is not a god.  But when they make to themselves gods of such as are not even p. 131 demons, by praying to unclean spirits, they are possessed by such as are not gods, but demons.  In like manner, because they have not been able to find for Mars any element or part of the world in which he might perform some works of nature of whatever kind, they have said that he is the god of war, which is a work of men, and that not one which is considered desirable by them.  If, therefore, Felicitas should give perpetual peace, Mars would have nothing to do.  But if war itself is Mars, as speech is Mercury, I wish it were as true that there were no war to be falsely called a god, as it is true that it is not a god.

Footnotes

Quasi medius currens.

Nuncius.

Enunciantur.