In the Decameron Day 2 Story 7, the protagonist is a princess of "Babylon" who has numerous sexual misadventures after getting shipwrecked on the way to be married. She is, I believe, suggested to be Muslim ("debarred by her law from the use of wine"), and at any rate certainly not Christian ("judging by what she observed of the customs of the people that she was amongst Christians"). Two passages in the story (emphasis mine below) refer to saints and crescents in a way that's opaque to me; I wonder if it refers to now-obscure saints or if there's some deeper symbolic or euphemistic meaning.
This new misadventure, following so hard upon the former, caused the lady no small chagrin; but Marato, with the aid of the good St. Crescent-in-hand that God has given us, found means to afford her such consolation that she was already grown so familiar with him as entirely to forget Pericone, when Fortune, not content with her former caprices, added a new dispensation of woe
The "consolation" here is presumably sexual, but is "the good St. Crescent-in-hand" also a euphemism? Or is it a real Christian saint, or an indirect/metonymous way of referring to one? Or is it an Islamic reference, via the crescent?
So, after long time conferring together, they set me on one of their horses and brought me to a house, where dwelt a community of ladies, religious according to their law; and what the men may have said I know not, but there I was kindly received and ever honourably entreated by all; and with them I did afterwards most reverentially pay my devotions to St. Crescent-in-Hollow, who is held in great honour by the women of that country.
This is part of the invented story that the princess tells her father at the end. Is "St. Crescent-in-Hollow" an entirely invented name for a Christian saint, or, again, does it refer to a real saint?
The original Italian for these phrases, as far as I can tell, is "santo cresci in man" and "san Cresci in Valcava".