word which could only proptrhj suggest an a priori scheme, deducing our knowledge from the intellect, has in France become the name peculiarly distinctive of that philosophy of mind which exclusively derives our knowledge from the senses." Instead of employing the terms image, species, phantasm, etc.,-\\-ith reference to the mental representation of external things, as had pre- viously been done, Descartes adopted the word idea. In this use of the word he was followed by other philos- ophers, as Leibnitz and Locke, who desired the word to stand for " whatever is the object of the understand- ing when a man thinks." Hence the mental impression that we are supposed to have when thinking of the sun, without seeing the actual object, is called our idea of the sun. The idea is thus in contrast with the sensa- tion, or the feeling that we have when the senses are engaged directly or immediatel}' upon the thing itself. The sensation is the result of the pressure of the object, and declares an external reality, the impression per- sisting after the thing has gone, and recoverable by mental causes without the original, is the idea. Al- though the word in this application may be so guarded as to lead to no bad consequences, Eeid {Intel/. Fotv. Ess. i, chap, i) most vehemently protested against its use in such a sense, holding that it gave countenance to the setting up of a new and fictitious element in the opera- tions of the mind. But this raises the great ques- tion of metaphysics, namely, the exact nature of our knowledge of an external world. Bishop Berkeley (q. v.), however, must be regarded as the true representa- tive of modern idealism. He held that " the qualities of supposed objects cannot be perceived distinct from the mind that perceives them ; and these qualities, it will be allowed, are all that we can know of such ob- jects. If, therefore, there were external bodies, it is im- possible we should ever know it ; and if there were not, we should have exactly the same reason for believing there were as we now have. All, therefore, which really exists is spirit, or ' the thinking principle' — ourselves, our fellow-men, and God. What we call ideas are present- ed to us by God in a certain order of succession, which order of successive presentation is what we mean by the laws of nature." Tliis mode of speculation of bishop Berkeley, which he defended with so much acuteness, and which Lewis {Hist, of Phil, ii, 283) now goes forth to defend, claiming that the bishop's critics misunder- stood him, he held to be the only [lossible true view of our nature and the government of God. But there is no question that, whatever benefits it may have bestow- ed upon the bishop and his immediate disciples, it has been found, practically, to lead to scrpticism. " By tak- ing away the grounds of a belief which is both natural and imiversal, and which cannot, at first, be even doubt- ed without a severe exercise of thought, it shook men's faith in all those primarj^ truths which are at once the basis of their Imowledge and the guides of their con- duct. It seemed to throw distrust on the evidence of the senses, as it really invalidated the si)ontaneous con- clusions which every man inevitably forms from that evidence." This theory is conclusively proved by the conduct of Hume; for, if a main pillar of the edifice could so easily be shaken, what was there to hinder from throwing do\vn the whole fabric? Beginning where Berkeley began, Hume proceeded much farther, and left unassailed hardly one article of human faith. He denied the reality not only of the object perceived, but of the mind perceiving. He reduced all thinking existence to a succession of rapidly fleeting ideas, each one being known only at the instant of its manifestation to consciousness, and then fading away, leaving no surely recognisable trace of itself on the memors', and affording no ground for an anticipation of the future. We do not even know, he maintains, that any one thing depends upon another in the relation of an effect to its cause. We know no true cause whatever, and our only idea of power is a fiction and a blunder. The conclusion of the whole matter, according to his philosophy, is, not the
mere negation of this or that positive belief, but univer- sal distrust of the human faculties, considered as means for the acquisition of truth. They contradict each o\h- er, and leave nothing certain except that nothing can be known. See Hume; Reid. The German philos- ophers Kant, Fichte, and Schelling, who are often class- ed among the idealistic school, used the word idea in the Platonic or transcendental sense. Hegel, on rhe other hand, modified the use of the word to sucli an ex- tent that his idealism does not only deser\-e to be called absolute-i&eSiMsm, but much more properly pantheistic, no less than the doctrine of the Eleatics anciently, or of Spinoza in modem times. It is thus apparent, from the looseness of the application of the word idea, and the danger of its not conveying a definite signification, that we need a general word in the English language which may more accurately express the contrast to sen- sation or to actuality. But, as no better has yet been fomid, it is difficult to avoid the use of ideality, "being what is common to memorj^ and to imagination, and expressing the mind as not under the present impression of real objects, but as, by its own tenacity and associa- tmg powers, having those objects to all practical ends be- fore its view. Thus all our sensations, whether of sight, hearing, touch, taste, or smell, and all the feelings that we have in the exercise of our moving energies, become transformed into ideas when, without the real presence of the original agency, we can deal with them in the way of pursuit or avoidance, or can discriminate and compare them, nearly as. if in their first condition as sensation." Sir W. Hamilton, in his Lectures on Logic (i, 126), has endeavored to avoid employing the word, but other writers on mental philosophy have freely adopted it in the above acceptation. See Chambers, Cyclop, v, 510 sq.; Krauth's Fleming, Yocah. of Philos. p. 222 sq. ; Brande and Cox, Diet, of Science, Lit. and ^r^, ii, 189; Moreli, History (f Philos. p. -^^ sq. ; Lewis, Hist, of Philos. (enlarged ed.), see Index; Farrar, Crit. Hist, of Free Thought, i>. 422; M'Cosh, Intuitions of the Mind, p. 317 sq. ; Morell's Tennemann, Hist, of Philos, see Index ; K.A. Rev. No. Ixxvi, p. 60 sq. ; Jour. Sac. Lit. XX, 298sq. See Nihilism; Realism. (J. H.W.)