39 – Read Leslie Stephen, _History of English Thought_, vol. i, pp. 86–88. 40 – Read Royce, _Spirit of Modern Philosophy_, p. 86; Rand, _Modern Classical Philosophers_, pp. 263–277. 41 – Berkeley and Hume were really also dualists, like Locke and all other Enlighteners. The ideas were substituted by them for material substances. As objects of knowledge the ideas were antithetical to the knowing process. Hume tried to overcome this dualism, but he was not successful in his attempt. 42 – Read Hibben, _The Philosophy of the Enlightenment_, chap. iii. 43 – Hibben, _Phil. of Enlightenment_, p. 64. 44 – Read Rand, _Modern Classical Philosophers_, pp. 326–342; Eucken, _Problem of Human Life_, pp. 420–422; Windelband, _Hist. of Phil._, pp. 472–476. 45 – Causal events are to Hume merely _alleged_ matters of fact. 46 – Read Eucken, _Problem of Human Life_, pp. 415–420. 47 – Voltaire’s _Letters on the English_ were written in 1728, published first in London, and appeared in France in 1734. His _Elements of the Philosophy of Newton_ was published in Amsterdam in 1738, but was not allowed to be published in France until 1741. 48 – Read Ueberweg, _Hist. of Phil._, vol. ii, pp. 124–125. 49 – Read Morley, _Diderot_, vol. i, ch. v, pp. 113–171. 50 – Read Rand, _Modern Classical Philosophers_, pp. 347–375. 51 – Read Eucken, _Problem of Human Life_, pp. 423–433. 52 – In a real sense the German Enlightenment has never come to an end. Classicism and the Romantic movement were a continuation of it. 53 – Read Windelband, _Hist. of Phil._, pp. 529–531. 54 – Read the quotation from Heine in E. Caird, _Phil. of Kant_, vol. i, p. 63; Stirling, _Textbook to Kant_, Biographical Sketch; Royce, _Spirit of Modern Philosophy_, chap. iv; Windelband, _Hist. of Phil._, pp. 532–534; Rand, _Modern Classical Philosophers_, pp. 376–405, 420–424; Eucken, _Problem of Human Life_, pp. 435–452. 55 – The word “world” is used for lack of a better. The reader is, however, again reminded that Kant’s problem is one of epistemology and not of metaphysics. 56 – Paulsen says (_Immanuel Kant, His Life and Teaching_, p. 135) that this formula of synthetic judgments _a priori_ appears only in the introduction to the _Critique_ and in Kant’s later writings, and it would have been no misfortune if Kant had never discovered it. But Windelband (_Hist. of Phil._, p. 533, n. 2) says, “No one who does not make this clear to himself has any hope of understanding Kant.” 57 – Quoted from Falckenberg, _Hist. of Modern Phil._, p. 387. This is a paraphrase of some of Schiller’s verses in _The Philosophers_, a satirical poem of philosophical theories.