Natural history, how necessary a study, iii. 54. Naturalism, general analysis of it with respect to art, ii. 181, 190; its advance in Gothic art, iii. 6; not to be found in the encrusted style, ii. 89; its presence in the noble Grotesque, iii. 144. Nature (in the sense of material universe) not improvable by art, i. 350; its relation to architecture, i. 351. Niches, use of, in Northern Gothic, i. 278; in Venetian, ii. 240; in French and Veronese, ii. 227. Norman hatchet-work, i. 297; zigzag, i. 339. Novelty, its necessity to the human mind, ii. 176. O Oak-tree, how represented in symbolical art, iii. 185. Obedience, how symbolized, ii. 334. Oligarchical government, its effect on the Venetians, i. 5. Olive-tree, neglect of, by artists, iii. 175; general expression of, iii. 176, 177; representations of, in mosaic, iii. 178. Order, uses and disadvantages of, ii. 172. Orders, Doric and Corinthian, i. 13; ridiculous divisions of, i. 157, 370; ii. 173, 249; iii. 99. Ornament, material of, i. 211; the best, expresses man's delight in God's work, i. 220; not in his own, i. 211; general treatment of, i. 236; is necessarily imperfect, i. 237, 240; divided into servile, subordinate, and insubordinate, i. 242, ii. 158; distant effect of, i. 248; arborescent, i. 252; restrained within limits, i. 255; cannot be overcharged if good, i. 406. Oxford, system of education at, i. 391. P Paganism, revival of its power in modern times, iii. 105, 107, 122. Painters, their power of perception, iii. 37; influence of society on, iii. 41; what they should know, iii. 41; what is their business, iii. 187. Palace, the Crystal, merits of, i. 409. Palaces, Byzantine, ii. 118, 391; Gothic, ii. 231. Papacy. See "Popery." Parapets, i. 162, ii. 240. Parthenon, curves of, ii. 127. Patience, how symbolized, ii. 334. Pavements, ii. 52. Peacocks, sculpture of, i. 240. Pedestals of shafts, i. 82; and see Venetian Index under head "Giorgio Maggiore." Perception opposed to knowledge, iii. 37. Perfection, inordinate desire of, destructive of art, i. 237; ii. 133, 158, 169. Perpendicular style, i. 190, 253; ii. 223, 227. Personification, evils of, ii. 322. Perspective, aerial, ridiculous exaggerations of, iii. 45; ancient pride in, iii. 57; absence of, in many great works, see in Venetian Index the notice of Tintoret's picture of the Pool of Bethesda, under head "Rocco." Phariseeism and Liberalism, how opposed, iii. 97. Philology, a base science, iii. 54. Piazzetta at Venice, plan of, ii. 283; shafts of, ii. 233. Pictures, judgment of, how formed, ii. 371; neglect of, in Venice, ii. 372; how far an aid to religion, ii. 104, 110. Picturesque, definition of term, iii. 134. Piers, general structure of, i. 71, 98, 118. Pilgrim's Progress. See "Bunyan." Pine of Italy, its effect on architecture, i. 152; of Alps, effect in