The theory has been attractively argued that next Sunday's EF and BCP collect was originally composed during the Papal campaign to get the Lupercalia celebrations in Rome banned (when the the Luperci brethren, naked but for a thong, ran through the streets whipping the outstretched hand of the citizenesses - who hoped thereby to secure fertility). The prayer expresses the hope that the Roman aristocracy will relinquish pagan residues incompatible with their Christian Faith. I rather like the word respuere (BCP eschew those those things that are contrary ...), which really means spit back out.
Memories crowd in of all those old notices whereby English town councils tried to preserve genteel ladies from the offensive spitting of the lower orders (somebody ought to start a museum for surviving examples; and for other old favourites like Commit No Nuisance, and Kindly Adjust Your Clothing Before Leaving The Convenience).
But we know from first millennium documentation that part of the entourage, as the Pope on horseback made his solemn way through the streets of Rome, was a subdeacon carrying a bowl for the Sovereign Pontiff to expectorate into.
And long-time readers, who read my series on the Pax in the Roman Rite, will recall the fact that scrupulous worshippers regarded the Kiss of Peace as breaking a fast.
Then there is the gospel-based use, in the EF form of Baptism, of presbyteral saliva to open the mouths of the baptizands. Curious that ritual innovators like Bubbles Stancliff have not thought to revive that beautiful old rite, so full of pastoral and catechetical possibilities.
Now if I were a really sophisticated mystagogue, I would be able to weave all the above into a coherent exposition with a compelling point at the end of it.