Then, after the conversation had continued
for some little time, Wieland declared warmly that he thought that he
had chosen rightly. "I understand your nature," he said; "keep to
philosophy." And, later, he told Johanna Schopenhauer that he thought
her son would be a great man some day.

Towards the close of the summer of 1811 Schopenhauer removed to Berlin
and entered the University. He here continued his study of the natural
sciences; he also attended the lectures on the History of Philosophy by
Schleiermacher, and on Greek Literature and Antiquities by F.A. Wolf,
and the lectures on "Facts of Consciousness" and "Theory of Science" by
Fichte, for the last of whom, as we know indeed from frequent references
in his books, he had no little contempt. A year or so later, when the
news of Napoleon's disaster in Russia arrived, the Germans were thrown
into a state of great excitement, and made speedy preparations for war.
Schopenhauer contributed towards equipping volunteers for the army, but
he did not enter active service; indeed, when the result of the battle
of Luetzen was known and Berlin seemed to be in danger, he fled for
safety to Dresden and thence to Weimar. A little later we find him at
Rudolstadt, whither he had proceeded in consequence of the recurrence of
differences with his mother, and remained there from June to November
1813, principally engaged in the composition of an essay, "A
Philosophical Treatise on the Fourfold Root of the Principle of
Sufficient Reason," which he offered to the University of Jena as an
exercise to qualify for the degree of Doctor of Philosophy, and for
which a diploma was granted. He published this essay at his own cost
towards the end of the year, but it seems to have fallen flatly from the
press, although its arguments attracted the attention and the sympathy
of Goethe, who, meeting him on his return to Weimar in November,
discussed with him his own theory of colour. A couple of years before,
Goethe, who was opposed to the Newtonian theory of light, had brought
out his _Farbenlehre_ (colour theory). In Goethe's diary Schopenhauer's
name frequently occurs, and on the 24th November 1813 he wrote to
Knebel: "Young Schopenhauer is a remarkable and interesting man.... I
find him intellectual, but I am undecided about him as far as other
things go." The result of this association with Goethe was his _Ueber
das Sehn und die Farben_ ("On Vision and Colour"), published at Leipzig
in 1816,