Johannes Gutenberg, German blacksmith, goldsmith, inventor, printer, publisher, entrepreneur, invented metal movable type in about 1440. He adapted the use of metal type to a screw press (already available) to form a printing press that enabled the rapid production of books, the first of which was the Gutenberg Bible. Similar printing presses were built all over Europe, and millions of books appeared and were distributed thereafter. This was the information revolution of that distant age.
The writings and pictures by Martin Luther (1483-1546), Ulrich Zwingli (1484-1531), and John Calvin( 1509-1564 were printed on Gutenberg presses and their wide-spread availablity was critical to the initiation of the Protestant Reformation.
William Gilbert (1544-1603), an English scientist and physician to Queen Elizabeth I, published Die Magnete in 1600 which was his pioneering work in experimental science. In it he presented the structure and procedures of experimental science for the first time, and this was arguably the greatest invention of secular humanity for all time. The Gutenberg printing press sped the dissemination of the scientific method across the literate world.
These bookends, entitled Ye Olde Printer, depict a Gutenberg printing press. The printer moves a handle which turns a screw, and the screw presses a plate of inked type to a medium of paper or other material. The words formed by the inked type are transferred to the paper this way. The screw is visible at the back of the press. The immensely significant Gutenberg press is certainly a suitable subject for bookends.
UPDATE: Chris Bernhard sent photos of his Ye Olde Printer bookends. They are also sculpted by J. Ruhl and produced by Armor Bronze and are taller and more colorful. And they are a good addition to the post.