St. Augustine, writing with Varro before him, finds no less than three spirits of the entrance to a house: Forculus, of the door itself; Limentinus, of the threshold; and Cardea, of the hinges of the door; and these Varro seems to have found in the books of the pontifices.[156] I must postpone the question as to what these pontifical books really represented; but the passage will at least serve to show us the popular anxiety about the point of entrance to a house, and its association with the spirit world. Of late sober research has reached the conclusion that the original door-spirit was Janus, whom we know in Roman history as residing in the symbolic gate of the Forum, and as the god of beginnings, the first deity to be invoked in prayer, as Vesta was the last.[157] But Janus is also wanted for far higher purposes by some eminent Cambridge scholars; they have their own reasons for wanting him as a god of the sky, as a double of Jupiter, as the mate of Diana, and a deity of the oak.[158] So, too, he was wanted by the philosophical speculators of the last century B.C., who tried to interpret their own humble deities in terms of Greek philosophy and Greek polytheism. The poets too, who, as Augustine says, found Forculus and his companions beneath their notice, played strange tricks with this hoary old god, as any one may read in the first book of Ovid's _Fasti_. I myself believe that the main features of the theology (if we may use the word) of the earliest Rome were derived from the house and the land as an economic and religious unit, and I am strongly inclined to see in Janus bifrons of the Forum a developed form of the spirit of the house-door; but the question is a difficult one, and I shall return to it in a lecture on the deities of early Rome.