There are 14 of these glasses around the world, and their origins are a mystery, save that a handful of them were known to be used by a Silesean princess who became a devout (crazily devout - she washed her grand-children's faces in the water she had used to wash the feet of nuns...) Christian, in the early days when devotion to Christ meant giving up everything else.
She gave up drinking wine and, in those days, taking up drinking water from a public well meant exposing yourself to all manner of deadly, water-borne diseases. Her husband worried for her health, but seemed more concerned with her physical health than her mental state - thirst things first.
But then he noticed that when she held this cup - filled with unclean water - to her lips, Christ protected her by turning it into wine before she drank, so that put his mind at rest on both counts.
Those of you who know me a little, know that there are two things that occupy quite a large amount of my leisure time - the acquisition of fine, antique drinking-glasses, and the consumption of wine from them. Wouldn't this glass be just perfect for my compact but adorable, city apartment?
I cannot help thinking that I may have to - paradoxically - renounce wine for this little trick to work, but I am willing to give it a try, so if you stumble across a 15th version of this glass which isn't in a museum, please let me know, and I will make it worth your while.