This threatened paralysis awoke Reid into his characteristic intellectual life. He was among the first in Europe to see the far-reaching meaning of Hume’s account of man’s condition. He found in it the deep-lying seeds of modern agnosticism. Its rashness was confessed by its author. ‘I acknowledge a very great mistake in conduct in publishing my _Treatise of Human Nature_, a book which pretended to innovate in all the sublimest parts of philosophy, and which I composed before I was five-and-twenty. But what success the same doctrines better illustrated and expressed may meet with _adhuc sub judice lis est_. I wish I had always confined myself to the more easy parts of erudition.’ Accordingly, about ten years after, Hume presented his ‘sceptical doubts’ in a milder form, and accompanied by a ‘sceptical solution’ of them, in an _Inquiry Concerning Human Understanding_; but it was Hume in the original _Treatise_, not as recast in the _Inquiry_, that moved Reid. Kant, like Reid, was awakened from what he calls his ‘dogmatic slumber’ by David Hume; but it was the _Inquiry_, not the _Treatise_, of which last he appears ignorant, that roused Kant. Reid grappled with the more open and all-pervading uncertainties of the earlier work. Let us look into the book which appalled the young minister of New Machar by the spectre of a meaningless universe and illusory human nature. Its author seemed to be indulging in ‘a peculiar strain of humour when he set out in his introduction by promising with a grave face no less than a complete system of the sciences upon a foundation entirely new, namely, human nature, while the intention of the whole work is to show that there is neither human nature nor science in the world. He surely believed, against his principles, that he should be read, and that he should retain his personal identity till he reaped the reputation justly due to his metaphysical acumen.’ Reid found him taking for granted as his fundamental maxim, that nothing can be admitted as true which cannot be logically deduced from impressions of sense. Hume found the impressions of sense to be transitory, and distinguished in their succession by degrees of intensity,—sensations when in their highest intensity, memories when in an abated degree, and mere fancies when the intensity is at a minimum. His maxim forbade recognition of more reality in the universe than a momentary reality of isolated perceptions, in their different degrees of intensity, but without any reasonable retrospective memory, or any reasonable expectation with its hopes or fears. What we call ‘existence’ was resolved into an unintelligible chaos of felt impressions—a purposeless procession, in which the percipient loses his very selfhood and all besides. The Past, the Distant, the Future, are all illusions. ‘Things’ and ‘persons’ are only unconnected transitory feelings, without any permanent person to feel them. The word ‘identity’ is meaningless.