a phrase, purporting to express an ‘abstract conception,’ expresses any actual idea or no, his test is, ‘Point out the impression from which the idea, if there be any, is derived’--a test which has clearly no significance if the impression is merely the idea itself at a livelier stage (for a person, claiming to have the idea, would merely have to say that he had never known it more lively, and that, therefore, it was itself an impression, and the force of the test would be gone), but which seems so satisfactory because the impression is regarded as the direct effect of outward things, and thus as having a prerogative of reality over any perception to which the mind contributes anything of its own. By availing himself alternately of this popular conception of the impression of sensation and of his own account of it, he gains a double means of suppressing any claim of thought to originate. Every idea, by being supposed in a more lively state, can be represented as derived from an impression, and thus (according to the popular notion) as an effect of something which, whatever it is, is not thought. If thereupon it is pointed out that this outward something is a form of substance which, according to Hume’s own showing, is a fiction of thought, there is an easy refuge open in the reply that ‘impression’ is only meant to express a lively feeling, not any dependence upon matter of which we know nothing. [1] p. 317 [Book I, part I., sec. III.] So the ‘Positivist’ juggles with ‘phenomena’. 202. Thus the way is prepared for the juggle which the modern popular logic performs with the word ‘phenomenon’--a term which gains acceptance for the theory that turns upon it because it conveys the notion of a relation between a real order and a perceiving mind, and thus gives to those who avail themselves of it the benefit of an implication of the ‘noumena’ which they affect to ignore. Hume’s inconsistency, however, stops far short of that of his later disciples. For the purpose of detraction from the work of thought he availed himself, indeed, of that work as embodied in language, but only so far as was necessary to his destructive purpose. He did not seriously affect to be reconstructing the fabric of knowledge on a basis of fact. There occasionally appears in him, indeed, something of the charlatanry of common sense in passages, more worthy of Bolingbroke than himself, where he writes as a champion of facts against metaphysical jargon. But when we get behind the mask of concession to popular prejudice, partly ironical, partly due to his undoubted vanity, we find much more of the ancient sceptic than of the ‘positive philosopher.’ Essential difference, however, between Hume and the ‘Positivist’.