I've just been reading about Anglo-Saxon ordeals. The ordeal of hot water, where the defendant was obliged to plunge his hand into boiling water to retrieve a stone, put in mind of this phrase. 'Aha!' I thought. 'This must be where our modern saying derives from.' I have, however, been wrong before. I recall once proudly announcing to my best friend in Durham that I had worked out why Prebend's Bridge was named thus. 'It's because its before the bend; it's 'pre' the bend.' She put me out of my ignorant misery, but really, words like prebend, who knew those?! That first year at Durham I spent a quite a while wondering where I could get my hands on that immensely useful book 'ibid.', some sort of encyclopedic reference book one could only presume. Yes, I expect you're laughing, but only if your schooling included exposure to Latin.