The founder of the _transcendental_ philosophy very properly insists on the distinction between the sensitive and the intellectual faculties, and makes this division the ground-work of his entire system. He considers the joint operation of these different powers as necessary to all our knowledge, and enumerates with scrupulous formality the different ideas which originate in this complex progress, and points out the share which each has in each. The author conceives of certain general ideas, as _substance_ and _accident_, _cause_ and _effect_, _totality_, _number_, _quantity_, _relation_, _possibility_, _necessity_, etc. as pure ideas of the understanding; and he classes _space_ and _time_ as primary forms of the sensitive faculty.[9] All this may be very true; but the proof may also be required, and it is not given. Yet modern metaphysicians are not likely, either as sceptical inquirers after truth, or as lovers of abstruse paradoxes, to be satisfied with the bare assumption of a common prejudice. They will say, either that all these ideas have no real existence in the mind, that they are mere abstract terms which owe their force and validity to the mechanism of language; or admitting their existence in the mind, they will contend with Locke, that they are only general, reflex, and compound ideas, originally derived from sensation. ‘Whence do all the ideas and operations of the mind proceed?’ _From experience_, is the answer given by the modern philosophy—_From experience and from the understanding_, is the answer given by Kant. The former solution has the advantage of simplicity; and the logical proof is wanting to the latter. To compare grave things with gay, the display which this celebrated philosopher makes of his categories, his forms of the sensitive faculty, his pure ideas, and _à priori_ principles, somewhat resembles the method taken by Sir Epicure Mammon in _The Alchymist_ to persuade his sceptical friend that he is about to discover the philosopher’s stone by overpowering his imagination with the description of the fine things he will do when he has it:—‘And all this I will do with the stone.’ ‘But will all this give you the stone?’ says Pertinax Surly, who ‘will not believe antiquity’ any more than our modern sceptics.