We have blogged before about Nicolas Jenson's obsession with the perfect page and his devotion to an austere typography, so we don't have much to say about this book, except to exclaim, "Damn, look at that page!"
This is Jenson's 1476 printing of Pliny's Natural History, translated into Italian by Christophoro Landino. The size of the book is daunting, then you open it up and see the luxurious margins Jenson provided to set off his unrelenting text block. Purity of form.
To see it ask for Incunabula 137.