I would suggest that we may see in it the connecting link between that group and the individual adult males within it; in that case the Genius would be that soul of a man which enables him to fulfil the work of continuing the life of the gens. We can easily imagine how it might eventually come to be his guardian spirit, and to acquire all the other senses with which we are familiar in Roman literature. With the development of the idea of individuality, the individuality of a man as apart from the kin group, the idea of the individuality of the Genius also became emphasised, until it became possible to think of it as even living on after the death of its companion;[152] in this way, in course of time, the Genius came to exercise a curious influence on the idea of the Manes. The history of the idea of Genius, and its application to places, cities, etc., is indeed a curious one, and of no small interest in the study of religion; but we must return to the primitive house and its divine inhabitants. There is one more of these who calls for a word before I pass to the land and the boundaries; we meet him on the threshold as we leave the dwelling. It is, of course, well known to anthropologists that the door of a house is a dangerous point, because evil spirits or the ghosts of the dead may gain access to the house through it. Among the innumerable customs which attest this belief there are one or two Roman ones, _e.g._ the practice of making a man, who has returned home after his supposed death in a foreign country, enter the house by the roof instead of the door; for the door must be kept barred against ghosts, and this man may be after all a ghost, or at least he may have evil spirits or miasma about him.[153] It was at the doorway that a curious ceremony took place (to which I shall ask your attention again) immediately after the birth of a child, in order to prevent Silvanus, who may stand for the dangerous spirits of the forest, from entering in and vexing the baby.[154] Again, a dead man, as among so many other peoples, was carried out of the doorway with his feet foremost, so that he should not find his way back; and the old Roman practice of burial by night probably had the same object.[155] Exactly the same anxiety (_religio_) is seen in regard to the gates of a city; the wall was in some sense holy (_sanctus_), but the gates, through which was destined to pass much that might be dangerous, could not be thus sanctified. Was there, then, no protecting spirit of these doors and gates?