form which has been given them does not assist but hinders æsthetic contemplation. Manufactured articles also serve to express Ideas, only it is not the Idea of the manufactured article which speaks in them, but the Idea of the material to which this artificial form has been given. This may be very conveniently expressed in two words, in the language of the schoolmen, thus,—the manufactured article expresses the Idea of its _forma substantialis_, but not that of its _forma accidentalis_; the latter leads to no Idea, but only to a human conception of which it is the result. It is needless to say that by manufactured article no work of plastic art is meant. The schoolmen understand, in fact, by _forma substantialis_ that which I call the grade of the objectification of will in a thing. We shall return immediately, when we treat of architecture, to the Idea of the material. Our view, then, cannot be reconciled with that of Plato if he is of opinion that a table or a chair express the Idea of a table or a chair (De Rep., x., pp. 284, 285, et Parmen., p. 79, ed. Bip.), but we say that they express the Ideas which are already expressed in their mere material as such. According to Aristotle (Metap. xi., chap. 3), however, Plato himself only maintained Ideas of natural objects: ὁ Πλατων εφη, ὁτι ειδη εστιν ὁποσα φυσει (_Plato dixit, quod ideæ eorum sunt, quæ natura sunt_), and in chap. 5 he says that, according to the Platonists, there are no Ideas of house and ring. In any case, Plato’s earliest disciples, as Alcinous informs us (_Introductio __ in Platonicam Philosophiam_, chap. 9), denied that there were any ideas of manufactured articles. He says: Ὁριζονται δε την ιδεαν, παραδειγμα των κατα φυσιν αιωνιον. Ουτε γαρ τοις πλειστοις των απο Πλατωνος αρεσκει, των τεχνικων ειναι ιδεας, οἱον ασπιδος η λυρας, ουτε μην των παρα φυσιν, οἱον πυρετου και χολερας, ουτε των κατα μερος, οἱον Σωκρατους και Πλατωνος, αλλ᾽ ουτε των ευτελων τινος, οἱον ρυπου και καρφους, ουτε των προς τι, οἱον μειζονος και ὑπερεχοντος; ειναι γαρ τας ιδεας νοησεις θεου αιωνιους τε και αυτοτελεις (_Definiunt autem_ IDEAM _exemplar æternum eorum, quæ secundum naturam existunt. Nam plurimis ex iis, qui Platonem secuti sunt, minime placuit, arte factorum ideas esse, ut clypei atque lyræ; neque rursus eorum, quæ prætor naturam, ut febris et choleræ, neque particularium, ceu Socratis et Platonis; neque etiam rerum vilium, veluti sordium et festucæ; neque relationum, ut majoris et excedentis: esse namque ideas intellectiones dei æternas, ac seipsis perfectas_). We may take this opportunity of mentioning another point in which our doctrine of Ideas differs very much from that of Plato. He teaches (De Rep., x., p. 288) that the object which art tries to express, the ideal of painting and poetry, is not the Idea but the particular thing. Our whole exposition hitherto has maintained exactly the opposite, and Plato’s opinion is the less likely to lead us astray,