Crevier's continuation of Rollin, I believe, gives the best account of the Roman emperors down to Constantine. What shocking instances will you there meet with, of the terrible effects of lawless power on the human mind! How will you be amazed to see the most promising characters changed by flattery and self-indulgence into monsters that disgrace humanity! To read a series of such lives as those of Tiberius, Nero, or Domitian, would be intolerable, were we not consoled by the view of those excellent emperors, who remained uncorrupted through all temptations. When the mind--disgusted, depressed, and terrified--turns from the contemplation of those depths of vice, to which human nature may be sunk, a Titus, the delight of mankind--a Trajan--an Antoninus--restore it to an exulting sense of the dignity, to which that nature may be exalted by virtue. Nothing is more awful than this consideration: a human creature given up to vice is infinitely below the most abject brute; the same creature, trained by virtue to the utmost perfection of his nature, 'is but a little lower than the angels, and is crowned with glory and immortality.' Before you enter upon the modern history of any particular kingdom, it will be proper to gain some idea of that interval between ancient and modern times, which is justly called the dark and barbarous ages, and which lasted from Constantine to Charlemagne--perhaps one might say to some centuries after. On the irruption of the northern Barbarians, who broke the Roman empire, and dissipated all the treasures of knowledge, as well as of riches, which had been so long accumulating in that enormous state, the European world may be said to have returned to a second infancy; and the Monkish legends, which are the only records preserved of the times in which they were written, are not less fabulous than the tales of the demi-gods. I must profess myself ignorant how to direct you to any distinct or amusing knowledge of the History of Europe during this period[31]: some collect it from _Puffendorf's Introduction_; some from _The Universal History_; and now, perhaps, with more advantage and delight, from the first volume of _Robertson's Charles the Fifth_, in which he traces the progress of civilization, government, and arts, from the first settlements of the Barbarians; and shows the foundation of the several states into which Europe is now divided, and of those laws, customs, and politics, which prevail in this quarter of the world. In those dark ages, you will find no single character so interesting as that of Mahomet; that bold impostor, who extended his usurped dominion equally over the minds and properties of men, and propagated a new religion, whilst he founded a new empire, over a large portion of the globe. His life has been written by various hands.