Materialism and positivism soon came also to replace the visions of Herzen; for when Alexander II. opened the frontiers which the inflexible Nicholas had closed, the students brought home new idols from the German universities. Schopenhauer and Buchner superseded Hegel and Feuerbach. Schopenhauer, with his pessimism, his theory of Nirvana and universal annihilation, arrived just in time to foster the germs of fatalism dormant within the Russian soul; and Buchner, by means of his very superficial but eloquent book, was also in season to offer an accessible, clear, and popular formula to unthinking minds and negative or indolent temperaments; "Force and matter" was for a time the Bible of Russian students. It will be readily seen that the revolutionary formula and methods in Russia always came from abroad; but they met with tendencies which were unexpected, even though they proved favorable to development. The philosophy of nihilism was drawn from Western sources, no doubt; yet this phenomenon made its appearance only in Russia, a land predisposed to realism and mysticism, to brutality and languor, and above all to melancholy limitless as its plains. We are told of the now famous saying of a nihilist, who, being asked his doctrines, replied, "To see earth and heaven, Church and State, God and king, and to spit upon them all!" Although the verb to _spit_ is not so offensive in Russia as here, and is rather a sign of repugnance than of insult, such a reply contains the sum of negative nihilism; and negation, the critical period, cannot last longer than the despairing sigh of the dying. The active phase of nihilism, the reign of terror, passed by quickly, and now the party is beginning to lay aside its ferocious radicalism and deal with realities. VI. The Reign of Terror.