Carna was a nymph of the sacred "lucus" of Helernus, made goddess of hinges by Janus with the name of Cardea, and had the power of protecting and purifying thresholds and the doorposts. This would be a further element in explaining the role of Juno in the "Tigillum". It was also customary for new brides to oil the posts of the door of their new homes with wolf fat. In the myth of Janus and Carna (see section below) Carna had the habit when pursued by a young man of asking him out of shyness for a hidden recess and thereupon fleeing: but two headed Janus saw her hiding in a crag under some rocks. Thence the analogy with the rite of the Tigillum Sororium would be apparent: both in the myth and in the rite Janus, the god of motion, goes through a low passage to attain Carna as Horatius passes under the "tigillum" to obtain his purification and the restitution to the condition of citizen eligible for civil activities, including family life. The purification is then the prerequisite for fertility. The custom of attaining lustration and fertility by passing under a gap in rocks, a hole in the soil or a hollow in a tree is widespread.