The first printers could only print in one colour at a time, usually black. All the other colours had to be added later by hand. This is why the initial letters in the oldest books were drawn by hand, as in this work by Caesarius van Heisterbach. The text is printed in black, with hand-painted initials in red. Heisterbach wrote the Dialogus miraculorum, a textbook for monks in the form of dialogues, in the thirteenth century. The text was still in demand two hundred years later. Which is proven by this edition.