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.