HKB
archetypes of all the empirical objects of thought, as from its employment by Locke, who used it to express "whatsoever is the object of the understanding when a man thinks."
[75:1] "If we take as the utmost bounds of this system the orbit Uranus, we shall find that it occupies a portion of space not less than three thousand six hundred millions of miles in extent. The mind fails to form an exact notion of a portion of space so immense; but some faint idea of it may be obtained from the fact, that, if the swiftest race-horse ever known, had begun to traverse it at full speed, at the time of the birth of Moses, he could only as yet have accomplished half his journey."--Vestiges of the Natural History of Creation, pp. 1-2. Here an attempt is made to give a conception of abstract numbers, by calling up in the mind the ideas deposited there from actual impressions. Hume had, in the application of his theory to mathematics, to struggle with the fact that no truths had a clearer and more distinct existence in the mind than the abstract truths of the exact sciences; and feeling the difficulty he thus had to encounter, he did not recur in his subsequent works to this part of the sceptical theory. Kant seems to have filled up the blank for him, by treating those truths as synthetical intuitions anterior to experience in their abstract existence, though depending on experience in the knowledge of their concrete application; but it may be observed, that at the beginning of sect. 4. of his Inquiry, Hume seems to have nearly anticipated some such principle.
[76:1] "If any impression gives rise to the idea of self, that impression must continue invariably the same, through the whole course of our lives: since self is supposed to exist after that manner. But there is no impression constant and invariable. Pain and pleasure, grief and joy, passions and sensations, succeed each other, and never all exist at the same time. It cannot, therefore, be from any of these impressions, or from any other, that the idea of self is derived; and consequently there is no such idea. . . . . For my part, when I enter most intimately into what I call myself, I always stumble on some perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe any thing but the perception."--Treatise, B. i. p. iv. sect. 6.
[81:1] One cannot escape a feeling of astonishment on finding so great a philosopher as Reid saying, (Active Powers, ch. ix.) that on this theory day and night might be called mutually the cause and effect of each other, on account of their mutual sequence: as if the observation of those who have gone so far in civilisation as just to have seen ignited bodies, had not data for concluding that that phenomenon which most uniformly preceded the ramification of rays of light, was the appearance of a luminous body.
[82:1] This refers to the notion, which may now be termed obsolete, at least in philosophy, of an inherent power in the cause to produce the effect--not to Kant's theory, which does not appear to be inconsistent with the scientific application of Hume's.