Two-faced Janus (Ianus), presumed to be native to Italy, is the god of beginnings/endings. It's after Janus that the first month of the year, Januarius 'January', is named. The kalends (the 1st) of each month may have been dedicated to him.
Janus BasicsJanus is the Roman two-faced god of doorways and beginnings. His own shrine (to Janus Geminus), contained a bronze statue of the god. It was two arched gates with double doors that were closed very rarely, in times of peace. During war, the doors were open. The troops are thought to have marched through the arches, perhaps in a ritual of purification. Legend has the door of the shrine of Janus closed during the Roman Republic under Numa Pompilius, an early king of Rome, then in 235 B.C., and then under Augustus. No traces of the shrine of Janus in Rome have been found, although ancient writers say it was on the Argiletum by the Forum and it was represented on coins under the Emperor Nero.
Janus was usually the first of the gods to receive offerings. Consuls entered office on the Kalends of his month -- January.
Janus and the Salian Priests
Holding sacred shields, Salian priests sang a hymn to Janus. This hymn includes lines that have been translated as:
"Come forth with the cuckoo [in March] Truly all things dost thou make open.
Thou art Janus Curiatius, the good creator art thou.
Good Janus is coming, the chief of the superior rulers."
- "The Salian Hymn to Janus"
Rabun Taylor (citation below) eloquently describes the lack of a coherent story about Janus:
"Janus, like so many ancient gods who lacked the grace of a story, was a messy concrescence of scraps fallen from the table of memory. His incoherence was the cause of some puzzlement in the Roman Imperial era, and so he was periodically subjected to reassessments by master yarn-spinners like Ovid or by cosmologists and philosophers seeking to find profound symbolism in his duality."
A Transitional God: War, Peace, Crossings
Janus was not only a god of beginnings and transitions, but was also associated with war/peace since the doors of his shrine were opened except in times of peace. He may have been a god of stream crossings.
Ovid on the Myth of Janus
Ovid, the Augustan Age teller of mythological tales, provides a story about the early benefits conferred by Janus.
 "'I have learned much indeed; but why is the figure of a ship stamped on one side of the copper coin, and a two-headed figure on the other?' 'Under the double image,' said he, 'you might have recognized myself, if the long lapse of time had not worn the type away. Now for the reason of the ship. In a ship the sickle-bearing god came to the Tuscan river after wandering over the world. I remember how Saturn was received in this land: he had been driven by Jupiter from the celestial realms. From that time the folk long retained the name of Saturnian, and the country, too, was called Latium from the hiding (latente) of the god. But a pious posterity inscribed a ship on the copper money to commemorate the coming of the stranger god. Myself inhabited the ground whose left side is lapped by sandy Tiber's glassy wave. Here, where now is Rome, green forest stood unfilled, and all this mighty region was but pasture for a few kine. My castle was the hill which the present age is accustomed to call by my name and dub Janiculum. I reigned in days when earth could bear with gods, and divinities moved freely in the abodes of men. The sin of mortals had not yet put Justice to flight (she was the last of the celestials to forsake the earth): honour's self, not fear, ruled the people without appeal to force: toil there was none to expound the right to righteous men. I had naught to do with war: guardian was I of peace and doorways, and these,' quoth he, showing the key, 'these be the arms I bear.'"
Ovid Fasti 1
The First of the Gods
Janus was also an augur and mediator, perhaps the reason he is named first among the gods in prayers. Taylor says Janus, as the founder of sacrifice and divination, since he can see the past and the future through his two faces, is the world's first priest.
Janus for Luck
It was Roman tradition at the New Year to give the god honey, cakes, incense and wine to buy favorable signs and a guarantee of good luck. Gold brought better results than baser coins.
"Then I asked," Why, Janus, when I placate other gods, do I bring incense and wine to you first?" "So that you may gain entry to whatsoever gods you wish," he replied, "through me, who guard the threshold." "But why are glad words spoken on your Kalends? And why do we give and receive best wishes?" Then the god, leaning on the staff in his right hand, said, "Omens are wont to reside in beginnings. You train your anxious ears on the first call, and the augur interprets the first bird he sees. The temples and ears of gods are open, no tongue intones wasted prayers, and words have weight." Janus had finished. I was not silent for long, but tagged his final words with words of my own. "What do your dates and wrinkled figs mean, or the gift of honey in a snow-white jar?" "The omen is the reason," said he - "so that the sweetness replicates events, and so that the year should be sweet, following the course of its beginnings."
Translation of Ovid Fast. 1.17 1-188 from Taylor's article)
- "The Salii and Campaigning in March and October"
J. P. V. D. Balsdon
The Classical Review, New Series, Vol. 16, No. 2 (Jun., 1966), pp. 146-147
- "The Salian Hymn to Janus"
TAPhA, Vol. 31, (1900), pp. 182-188
- "Janus Custos Belli"
The Classical Journal, Vol. 23, No. 8 (May, 1928), pp. 610-614
- "Problems about Janus"
The American Journal of Philology, Vol. 100, No.
- "The Shrine of Janus Geminus in Rome"
American Journal of Archaeology, Vol. 47, No. 4 (Oct. - Dec., 1943), pp. 437-440
- "Watching the Skies: Janus, Auspication, and the Shrine in the Roman Forum"
Memoirs of the American Academy in Rome, Vol. 45 (2000), pp. 1-40