According to the Guardian:
Sotheby's has announced it is to sell an extremely rare and perfectly conditioned first edition of St Augustine's complete works as edited by Erasmus. What makes the set of books even more special is the thousands of tiny red-ink corrections, amendments and commentaries, the majority of which have not been studied academically.
Pretty nifty. But you know what I'd like more? A first edition of the complete works of Bede. (Actually, I wouldn't mind any old reading copy of any edition of his extant works). While we're talking impossible things, I'd give my eye teeth to sneak into another stream of the multiverse and remove the copy of Hild's Life that was--must have been--written at Whitby Abbey sometime in the early eighth century. Damn I'd like to see that book...
What books--real or imaginary--would you like to see?