customary in those histories to ignore the slightly earlier 
     discovery of ways to print pictures and diagrams. A book, 
     so far as it contains a text, is a container of exactly 
     repeatable word symbols arranged in an exactly 
     repeatable order. Men have been using such containers 
     for at least five thousand years. Because of this it can be 
     argued that the printing of books was no more than a 
     way of making very old and familiar things more cheaply. 
     It may even be said that for a while type printing was little 
     more than a way to do with a much smaller number of 
     proof readings. Prior to 1501 few books were printed in 
     editions larger than that handwritten one of a thousand 
     copies to which Pliny the Younger referred in the second 
     century of our era. The printing of pictures, however, 
     unlike the printing of words from movable types, brought 
     a completely new thing into existence—it made possible