Speaking about pax in the proto-Christan epoch turned out to be a delicate matter, because around the year 300 pax became a key word in the Christian liturgy. It became the euphemism for a mouth-to-mouth kiss among the faithful attending services; pax became the camouflage for the osculum (from os, mouth), or the conspiratio, a commingling of breaths.

The Cultivation of Conspiracy (1998)