If there is any truth in this conjecture, it may explain very simply the origin of the double head of Janus, which has so long exercised the ingenuity of mythologists. When it had become customary to guard the entrance of houses and towns by an image of Janus, it might well be deemed necessary to make the sentinel god look both ways, before and behind, at the same time, in order that nothing should escape his vigilant eye. For if the divine watchman always faced in one direction, it is easy to imagine what mischief might have been wrought with impunity behind his back. This explanation of the double-headed Janus at Rome is confirmed by the double-headed idol which the Bush negroes in the interior of Surinam regularly set up as a guardian at the entrance of a village. The idol consists of a block of wood with a human face rudely carved on each side; it stands under a gateway composed of two uprights and a cross-bar. Beside the idol generally lies a white rag intended to keep off the devil; and sometimes there is also a stick which seems to represent a bludgeon or weapon of some sort. Further, from the cross-bar hangs a small log which serves the useful purpose of knocking on the head any evil spirit who might attempt to pass through the gateway. Clearly this double-headed fetish at the gateway of the negro villages in Surinam bears a close resemblance to the double-headed images of Janus which, grasping a stick in one hand and a key in the other, stood sentinel at Roman gates and doorways; and we can hardly doubt that in both cases the heads facing two ways are to be similarly explained as expressive of the vigilance of the guardian god, who kept his eye on spiritual foes behind and before, and stood ready to bludgeon them on the spot. We may, therefore, dispense with the tedious and unsatisfactory explanations which, if we may trust Ovid, the wily Janus himself fobbed off an anxious Roman enquirer.
To apply these conclusions to the priest of Nemi, we may suppose that as the mate of Diana he represented originally Dianus or Janus rather than Jupiter, but that the difference between these deities was of old merely superficial, going little deeper than the names, and leaving practically unaffected the essential functions of the god as a power of the sky, the thunder, and the oak. It was fitting, therefore, that his human representative at Nemi should dwell, as we have seen reason to believe he did, in an oak grove. His title of King of the Wood clearly indicates the sylvan character of the deity whom he served; and since he could only be assailed by him who had plucked the bough of a certain tree in the grove, his own life might be said to be bound up with that of the sacred tree. Thus he not only served but embodied the great Aryan god of the oak; and as an oak-god he would mate with the oak-goddess, whether she went by the name of Egeria or Diana. Their union, however consummated, would be deemed essential to the fertility of the earth and the fecundity of man and beast. Further, as the oak-god was also a god of the sky, the thunder, and the rain, so his human representative would be required, like many other divine kings, to cause the clouds to gather, the thunder to peal, and the rain to descend in due season, that the fields and orchards might bear fruit and the pastures be covered with luxuriant herbage.
The reputed possessor of powers so exalted must have been a very important personage; and the remains of buildings and of votive offerings which have been found on the site of the sanctuary combine with the testimony of classical writers to prove that in later times it was one of the greatest and most popular shrines in Italy. Even in the old days, when the champaign country around was still parcelled out among the petty tribes who composed the Latin League, the sacred grove is known to have been an object of their common reverence and care. And just as the kings of Cambodia used to send offerings to the mystic kings of Fire and Water far in the dim depths of the tropical forest, so, we may well believe, from all sides of the broad Latian plain the eyes and footsteps of Italian pilgrims turned to the quarter where, standing sharply out against the faint blue line of the Apennines or the deeper blue of the distant sea, the Alban Mountain rose before them, the home of the mysterious priest of Nemi, the King of the Wood. There, among the green woods and beside the still waters of the lonely hills, the ancient Aryan worship of the god of the oak, the thunder, and the dripping sky lingered in its early, almost Druidical form, long after a great political and intellectual revolution had shifted the capital of Latin religion from the forest to the city, from Nemi to Rome.
