[1] The earliest testimony in favour of Koster is contained in a
German volume published at Cologne in 1499, known as the _Chronicle of
Cologne_, which was printed by Ulrich Zell, originally of Mayence, and a
well-known follower of Gutenberg and his system. Under the heading “Of
the art of printing books, when and where, and by whom, was invented the
inexpressibly useful art of printing books,” the author says, “Although
the art, as now practised, was discovered at Mayence, nevertheless the
first idea came from Holland, and the Donati, which had been previously
printed there. Those books are therefore the origin of the art.”—See
_Humphreys_, ch. iii. and iv.