The rest of Schopenhauer's life in its external relations may be briefly summed up. For a few years, it was diversified by travels in Italy and elsewhere, and by an unsuccessful attempt at academical teaching in Berlin. In 1831 he moved to Frankfort, where he finally settled in 1833. He lived unmarried there till his death on the 21st of September 1860. The monument, already spoken of, was unveiled at Frankfort on the 6th of June 1895. The almost unbroken silence with which his great work was received, though it had a distempering effect on the man, did not discourage the thinker. The whole series of Schopenhauer's works, indeed, was completed before he attained anything that could be called fame. Constantly on the alert as he was to seize upon confirmations of his system, he published in 1836 his short work _On the Will in Nature_, pointing out verifications of his metaphysics by recent science. In 1839 his prize essay, _On the Freedom of the Human Will_ (finished in 1837), was crowned by the Royal Scientific Society of Drontheim in Norway. This and another essay, _On the Basis of Morality_, _not_ crowned by the Royal Danish Society of Copenhagen in 1840, he published in 1841, with the inclusive title, _Die beiden Grundprobleme der Ethik_. In 1844 appeared the second edition of his principal work, to which there was added, in the form of a second volume, a series of elucidations and extensions larger in bulk than the first. This new volume contains much of his best and most effective writing. His last work, _Parerga und Paralipomena_, which appeared in 1851 (2 vols.), is from the literary point of view the most brilliant. It was only from this time that he began to be well known among the general public; though the philosophic 'apostolate' of Julius Frauenstaedt, who afterwards edited his works, had begun in 1840. His activity was henceforth confined to modifying and extending his works for new editions; an employment in which he was always assiduous. In consequence of this, all of them, as they stand, contain references from one to another; but the development of his thinking, so far as there was such a process after 1818, can be easily traced without reference to the earlier editions. There is some growth; but, as has been said, it does not affect many of the chief points. A brief exposition of his philosophy can on the whole take it as something fixed. The heads under which it must fall are those assigned to the original four books of _Die Welt als Wille und Vorstellung_.