Cardea and Doorways
In the Christian polemic of the Church Fathers, Cardea is associated with two otherwise unknown deities who preside over doorways: Forculus, from fores, "door", plural in form because double doors were common on public buildings and elite homes (domūs); and Limentinus, from limen, liminis, "threshold" (compare English "liminal"). St. Augustine mocks the apparent triviality of these "little gods" in one of his "attacks against the multitude of Gods," noting that while one doorkeeper is adequate for a human household, the Roman gods require three: "evidently Forculus can't watch the hinge and the threshold at the same time." Modern scholarship has pointed out that this particular set of divinities belongs to rituals of marking out sacred space and fixing boundaries, religious developments hypothesized to have occurred during the transition from pastoralism to an agrarian society. Among Roman deities of this type, Terminus was the most significant.
Stefan Weinstock conjectured that these three doorway deities had a place in cosmology as the Ianitores terrestres, "doorkeepers of the earth," guarding the passage to the earthly sphere. In the schema presented by Martianus Capella, the Ianitores terrestres are placed in region 16 among deities of the lowest ranks, while Janus, the divine doorkeeper par excellence, is placed in region 1. This arrangement may represent the ianuae coeli, the two doors of the heavens identified with the solstices. Isidore of Seville says that there are two ianuae coeli, one rising (that is, in the East) and one setting (the West): "The sun advances from the one gate, by the other he recedes."
Isidore's definition is followed immediately by an explanation of the cardines (plural of cardo), the north-south pivots of the axis on which the sphere of the world rotates. These are analogous to the top-and-bottom pivot hinges of a Roman door.
In addition to the meaning of "door hinge," the cardo was also a fundamental concept in Roman surveying and city planning. The cardo was the main north-south street of a town, the surveying of which was attended by augural procedures that aligned terrestrial and celestial space. The cardo was also a principle in the layout of the Roman army's marching camp, the gates of which were aligned with the cardinal points to the extent that the terrain permitted.
Read more about this topic: Limentinus