Facts, however, do not always arrange themselves with the neatness which commends itself to an a priori historian, and the most recent students of block-books are unable to discover sufficient justification for the early dates which their predecessors assigned to them. On the old theory, in order to put it in front of the invention of printing with movable types, the _Biblia Pauperum_, which appears to be the oldest of the block-books, was placed about 1430 or 1440, and the _Ars Moriendi_ and the other chief specimens of block-printing were all supposed to have been produced before 1460, the main period of block-printing thus coinciding with the interval between the S. Christopher of 1423 and Pfister's activity at Bamberg about 1461. Positive evidence in favour of this chronology there was none. It rested solely on the idea, at which bibliographers had jumped, that the block-books were necessary "steps towards the invention of printing," as they have often been called, and on what seemed the improbability that any one, when the art of printing with movable type had once been invented, would have troubled himself laboriously to cut letterpress on wood. So far from block-printing being unable to co-exist with printing from movable type, it was not till nearly a century after printing had been invented that block-books finally ceased to be produced. The example generally quoted as the latest[4] is the _Opera nova contemplativa per ogni fedel christiano laquale tratta de le figure del testamento vecchio: le quale figure sonno verificate nel testamento nuovo_. As its title implies, this, curiously enough, is an adaptation of the _Biblia Pauperum_, which was thus the last, as it may have been the first, of the block-books. It is undated, but has the name of its publisher, Giovanni Andrea Vavassore, who worked at Venice about 1530.