[7] Schopenhauer, "Die Welt als Wille und Vorstellung," second edition, i., 37 (third edition, i., 39).
[8] See "Die Welt a. W. u. V.," vol. ii. pp. 17-21, and vol. i. p. 39 of the second edition. (The passages referred to by Schopenhauer in the second edition are in the third edition vol. ii. pp. 18-21, and vol. i. p. 40).
[9] Die Welt a. W. u. V., vol. i. p. 22 et seqq., and vol. ii. chap. ii. of the second edition; vol. i. p. 22, § 6, and vol. ii. chap. ii. of the third edition.
[10] The passage I have quoted above from Schopenhauer's letter is also to be found among the letters published in my book, "Arthur Schopenhauer. Von ihm, über ihn, u. s. w.," p. 541 et seqq., and it results from this, as well as from several other letters which likewise deal with important and knotty points in his philosophy, that this correspondence may perhaps not be quite so worthless and unimportant as many—among them Gwinner, in his pamphlet, "Schopenhauer und seine Freunde" (Leipzig, 1863)—represent it to be. This pamphlet of Gwinner's, by the way, has met with the treatment it deserves in the Preface to the collection, "Aus Arthur Schopenhauer's handschriftlichen Aphorismen und Nachlass. Abhandlungen, Anmerkungen, Fragmente." (Leipzig, 1864).
[11] Platon, "Phileb." pp. 219-223. "Politic." 62, 63. "Phædr." 361-363, ed. Bip. Kant, "Kritik der reinen Vernunft. Anhang zur transcend. Dialektik." English Translation by F. Max Müller. "Appendix to the Transc. Dialectic." pp. 551, and seqq.
[12] Kant, "Krit. d. r. V. Methodenlehre. Drittes Hauptstück," p. 842 of the 1st edition. Engl. Tr. by F. M. Müller. "Architectonic of Pure Reason," p. 723.
[13] "Meno." p. 385, ed Bip. "Even true opinions are not of much value until somebody binds them down by proof of a cause." [Translator's addition.]
[14] Aristot. "Metaph." v. 1. "All knowledge which is intellectual or partakes somewhat of intellect, deals with causes and principles." [Tr.'s add.]
[15] Here the translator gives Schopenhauer's free version of Wolf's formula.
[16] Platon, "Phileb." p. 240, ed Bip. "It is necessary that all which arises, should arise by some cause; for how could it arise otherwise?" [Tr.'s add.]