Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 7

Chapter 7.—Whether It is Reasonable to Separate Janus and Terminus as Two Distinct Deities.

Who, then, is Janus, with whom Varro commences?  He is the world.  Certainly a very brief and unambiguous reply.  Why, then, do they say that the beginnings of things pertain to him, but the ends to another whom they call Terminus?  For they say that two months have been dedicated to these two gods, with reference to beginnings and ends—January to Janus, and February to Terminus—over and above those ten months which p. 127 commence with March and end with December.  And they say that that is the reason why the Terminalia are celebrated in the month of February, the same month in which the sacred purification is made which they call Februum, and from which the month derives its name. 265   Do the beginnings of things, therefore, pertain to the world, which is Janus, and not also the ends, since another god has been placed over them?  Do they not own that all things which they say begin in this world also come to an end in this world?  What folly it is, to give him only half power in work, when in his image they give him two faces!  Would it not be a far more elegant way of interpreting the two-faced image, to say that Janus and Terminus are the same, and that the one face has reference to beginnings, the other to ends?  For one who works ought to have respect to both.  For he who in every forthputting of activity does not look back on the beginning, does not look forward to the end.  Wherefore it is necessary that prospective intention be connected with retrospective memory.  For how shall one find how to finish anything, if he has forgotten what it was which he had begun?  But if they thought that the blessed life is begun in this world, and perfected beyond the world, and for that reason attributed to Janus, that is, to the world, only the power of beginnings, they should certainly have preferred Terminus to him, and should not have shut him out from the number of the select gods.  Yet even now, when the beginnings and ends of temporal things are represented by these two gods, more honor ought to have been given to Terminus.  For the greater joy is that which is felt when anything is finished; but things begun are always cause of much anxiety until they are brought to an end, which end he who begins anything very greatly longs for, fixes his mind on, expects, desires; nor does any one ever rejoice over anything he has begun, unless it be brought to an end.

Footnotes

An interesting account of the changes made in the Roman year by Numa is given in Plutarch’s life of that king.  Ovid also (Fasti, ii.) explains the derivation of February, telling us that it was the last month of the old year, and took its name from the lustrations performed then:  Februa Romani dixere piamina patres.