text:  The great causes which have contributed to form the elements of modern society--the decaying civilization of Rome--the irruption of the northern nations--the prostration and degradation of the conquered people--the revival of the military spirit with the private wars of the nobles--the feudal system and institution of chivalry--the crusades and revival of letters following the capture of Constantinople by the Turks--the invention of printing and consequent extension of knowledge to the great body of the people--the discovery of the compass and with it of America by Columbus and doubling of the Cape of Good Hope by Vasco de Gama--the discovery of gunpowder and prodigious change thereby effected in the implements of human destruction--are all there treated in the most luminous manner and in general with the justest discrimination