(7) Where a vigorous but barbarian race overruns one much more civilised, there is similarly little prospect of immediate gain to progress, though after a period of independent growth the newer civilisation may be greatly fecundated by intelligent resort to the remains of the older. The cases of China and the Roman Empire may serve as illustrations. They were, however, different in that the northern invasion of Rome was by relatively considerable masses, while the Tartar conquerors of China were easily absorbed in the vast native population. (8) Where, again, independent States at nearly the same stage of civilisation, whether speaking the same or different languages, stand in a position of commerce and rivalry, but without desperate warfare, the friction and cross-fertilisation of ideas, together with the mixture of stocks, will develop a greater and higher intellectual and artistic life than can conceivably arise in one great State without great or close rivals, since there one set of ideals or standards is likely to overbear all others, with the result of partly stereotyping taste and opinion. This point is well put by Hume as to Greece, in his essay _Of the Rise of the Arts and Sciences_ (1752); and after him by Gibbon, ch. 53, Bohn ed. vi, 233; Cp. Heeren, _Pol. Hist. of Ancient Greece_, Eng. tr. p. 42; Walckenaer, _Essai_ cited, p. 338; Ferguson, _Essay on the History of Civil Society_, 1767, pp. 182, 183; Dunbar, _Essays on the History of Mankind_, 1780, pp. 257, 271; Goguet, _De l'origine des lois, des arts, et des sciences_, 1758, iii Epoque, L. ii, ch. 2; Salverte, _De la Civilisation_, 1813, pp. 83-88; Grote, _History of Greece_, pt. ii, ch. i, ed. 1888, ii, 156; Cunningham, _Western Civilisation_, i, 75. Grote brings out very clearly the "mutuality of action and reaction" in the case of the maritime Greeks as compared with the others and with other nations. See also Hegel, _Philos. der Geschichte_, Th. ii, Absch. i (ed. 1840, p. 275). Hegel, besides noting the abstract element of geographical variety, points to the highly mixed character of the Greek stocks, especially in Attica. So Salverte, as cited. The same principle is rightly put by Guizot (_Hist. de la civilisation en France_, i, leçon 2), and accepted by J.S. Mill (_On Liberty_, ch. iii, end), as a main explanation of the intellectual progress of modern Europe. It is therefore worth weighing as regards given peoples, by those who, like Mr. Bryce, see nothing but harm in the subdivision of Germany after the Thirty Years' War (_Holy Roman Empire_, 8th ed. p. 346). Against the undoubted evils connected with the partition system ought to be set the intellectual gains which latterly arose from it when the intellectual life of Germany had, as it were, recovered breath.