The compass, with its weird power of pointing north, guided the mariner on uncharted seas.

The obscure inventor of gunpowder revolutionized the art of war more than all the famous conquerors had done, and the polity of states more than any of the renowned legislators of antiquity.

The equally obscure inventor of mechanical clocks--a great improvement on the {8} older sand-glasses, water-glasses, and candles--made possible a new precision and regularity of daily life, an untold economy of time and effort.
[Sidenote: Printing] But all other inventions yield to that of printing, the glory of John Gutenberg of Mayence, one of those poor and in their own times obscure geniuses who carry out to fulfilment a great idea at much sacrifice to themselves.

The demand for books had been on the increase for a long time, and every effort was made to reproduce them as rapidly and cheaply as possible by the hand of expert copyists, but the applications of this method produced slight result.

The introduction of paper, in place of the older vellum or parchment, furnished one of the indispensable pre-requisites to the multiplication of cheap volumes.