Cardea or Carda was the ancient Roman goddess of the hinge (Latin cardo, cardinis), Roman doors being hung on pivot hinges. The Augustan poet Ovid conflates her with another archaic goddess named Carna, whose festival was celebrated on the Kalends of June and for whom he gives the alternative name Cranê or Cranea, a nymph. Ovid's conflation of the goddesses is likely to have been his poetic invention, but it has also been conjectured that Carna was a contracted form of Cardina, and at minimum Ovid was observing that their traditions were congruent.
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."