Coleridge, in his notebooks: ‘what a beautiful Thing urine is, in a Pot, brown yellow, transpicuous, the Image, diamond shaped of the Candle in it, especially, as it now appeared, I have emptied the Snuffers into it, & the Snuff floating about, painting all-shaped Shadows on the Bottom.’ [Seamus Perry (ed) Coleridge’s Notebooks: a Selection (OUP 2002), 52]
Which is all very nice, if a trifle self-regarding (he loves it because it's his urine; he wouldn't like a pot of my piss so much, I'd wager). And so, by a simple process of critical elaboration, to a whole thesis about Coleridge's intense self-absorption. But what really strikes me here is the sense of Latin punnery, conscious or otherwise. Urine in Latin is urina; pot in Latin urna; burnt-colour (brown, yellow) uro; 'to plunge into water', like a diver (or like an old snuffer) is urino. And shadow (umbra) isn't that far away. Coleridge seems to be piddling about in the 'U's.