But transported to Italy, the rite assumed a milder form. Within the sanctuary at Nemi grew a certain tree of which no branch might be broken. Only a runaway slave was allowed to break off, if he could, one of its boughs. Success in the attempt entitled him to fight the priest in single combat, and if he slew him he reigned in his stead with the title of King of the Wood (Rex Nemorensis).
According to the public opinion of the ancients the fateful branch was that Golden Bough which, at the Sibyl's bidding, Aeneas plucked before he essayed the perilous journey to the world of the dead. The flight of the slave represented, it was said, the flight of Orestes; his combat with the priest was a reminiscence of the human sacrifices once offered to the Tauric Diana.
This rule of succession by the sword was observed down to imperial times; for amongst his other freaks Caligula, thinking that the priest of Nemi had held office too long, hired a more stalwart ruffian to slay him; and a Greek traveller, who visited Italy in the age of the Antonines, remarks that down to his time the priesthood was still the prize of victory in a single combat.
Of the worship of Diana at Nemi some leading features can still be made out. From the votive offerings which have been found on the site, it appears that she was conceived of especially as a huntress, and further as blessing men and women with offspring, and granting expectant mothers an easy delivery.
Again, fire seems to have played a foremost part in her ritual. For during her annual festival, held on the thirteenth of August, at the hottest time of the year, her grove shone with a multitude of torches, whose ruddy glare was reflected by the lake; and throughout the length and breadth of Italy the day was kept with holy rites at every domestic hearth. Bronze statuettes found in her precinct represent the goddess herself holding a torch in her raised right hand; and women whose prayers had been heard by her came crowned with wreaths and bearing lighted torches to the sanctuary in fulfilment of their vows. Some one unknown dedicated a perpetually burning lamp in a little shrine at Nemi for the safety of the Emperor Claudius and his family. The terra-cotta lamps which have been discovered in the grove may perhaps have served a like purpose for humbler persons. If so, the analogy of the custom to the Catholic practice of dedicating holy candles in churches would be obvious. Further, the title of Vesta borne by Diana at Nemi points clearly to the maintenance of a perpetual holy fire in her sanctuary. A large circular basement at the north-east corner of the temple, raised on three steps and bearing traces of a mosaic pavement, probably supported a round temple of Diana in her character of Vesta, like the round temple of Vesta in the Roman Forum. Here the sacred fire would seem to have been tended by Vestal Virgins, for the head of a Vestal in terra-cotta was found on the spot, and the worship of a perpetual fire, cared for by holy maidens, appears to have been common in Latium from the earliest to the latest times. Further, at the annual festival of the goddess, hunting dogs were crowned and wild beasts were not molested; young people went through a purificatory ceremony in her honour; wine was brought forth, and the feast consisted of a kid cakes served piping hot on plates of leaves, and apples still hanging in clusters on the boughs.
But Diana did not reign alone in her grove at Nemi. Two lesser divinities shared her forest sanctuary. One was Egeria, the nymph of the clear water which, bubbling from the basaltic rocks, used to fall in graceful cascades into the lake at the place called Le Mole, because here were established the mills of the modern village of Nemi. The purling of the stream as it ran over the pebbles is mentioned by Ovid, who tells us that he had often drunk of its water. Women with child used to sacrifice to Egeria, because she was believed, like Diana, to be able to grant them an easy delivery. Tradition ran that the nymph had been the wife or mistress of the wise king Numa, that he had consorted with her in the secrecy of the sacred grove, and that the laws which he gave the Romans had been inspired by communion with her divinity. Plutarch compares the legend with other tales of the loves of goddesses for mortal men, such as the love of Cybele and the Moon for the fair youths Attis and Endymion. According to some, the trysting-place of the lovers was not in the woods of Nemi but in a grove outside the dripping Porta Capena at Rome, where another sacred spring of Egeria gushed from a dark cavern. Every day the Roman Vestals fetched water from this spring to wash the temple of Vesta, carrying it in earthenware pitchers on their heads. In Juvenal's time the natural rock had been encased in marble, and the hallowed spot was profaned by gangs of poor Jews, who were suffered to squat, like gypsies, in the grove. We may suppose that the spring which fell into the lake of Nemi was the true original Egeria, and that when the first settlers moved down from the Alban hills to the banks of the Tiber they brought the nymph with them and found a new home for her in a grove outside the gates. The remains of baths which have been discovered within the sacred precinct, together with many terra-cotta models of various parts of the human body, suggest that the waters of Egeria were used to heal the sick, who may have signified their hopes or testified their gratitude by dedicating likenesses of the diseased members to the goddess, in accordance with a custom which is still observed in many parts of Europe. To this day it would seem that the spring retains medicinal virtues.