Mental, adaptation, 214-235; completion of phenomena, 220; imagery, 253; imitation, our schematic, 199; processes, economical, 195; reproduction, 198; visualisation, 250. Mephistopheles, 88. Mercantile principle, a miserly, at the basis of science, 15. Mersenne, 377. Mesmerism, the mental state of ordinary minds, 228. Metaphysical establishment of doctrine of energy, 183. Metaphysical spooks, 222. Metrical, concepts of electricity, 107 et seq.; notions, energy and entropy are, 178; units, the building-stones of the physicist, 253. Metronomes, 41. Meyer, Lothar, his periodical series, 256. Middle Ages, 243, 349. Midsummer Night's Dream, 309. Mill, John Stuart, 230. Millers, school for, 326. Mill-wheel, doing work, 161. Mimicking facts in thought, 189, 193. Minor and major keys in music, 100 et seq. Mirror, symmetrical reversion of objects in, 92 et seq. Miserly mercantile principle at the basis of science, 15. Moat, child looking into, 208. Modern scientists, adherents of the mechanical philosophy, 188. Molecular theories, 104. Molecules, 203, 207. Molière, 234. Momentum, 184. Monocular vision, 98. Monotheism of the Christians and Jews, 187. Montagues and Capulets, 87. Moon, eclipse of, 219; lightness of bodies on, 4; the study of the, 90, 284. Moreau, 307. Mosaic of thought, 192. Motion, a perpetual, 181; quantity of, 184; the Eleatics on, 158; Wundt on, 158; the Herbartians on, 158. Motions, natural and violent, 226; their familiar character, 157. Mountains of the earth, would crumble if very large, 3; weight of bodies on, 112. Mozart, 44, 279. Müller, Johann, 291. Multiplication-table, 195. Multiplier, 132. Music, band of, its _tempo_ accelerated and retarded, 53; the principle of repetition in, 99 et seq.; its notation, mathematically illustrated, 103-104. Musical notes, reversion of, 101 et seq.; their economy, 192. Musical scale, a species of one-dimensional space, 105. Mystery, in physics, 222; science can dispense with, 189. Mysticism, numerical, 33; in the principle of energy, 184. Mythology, the mechanical, of philosophy, 207. Nagel, von, 364. Nansen, 296. Napoleon, picture representing the tomb of, 36. Nations, intercourse and ideas of, 336-337. Natural constants, 193. Natural law, a, not contained in the conformity of the energies, 175. Natural laws, abridged descriptions, 193; likened to type, 193. Natural motions, 225. Natural selection in scientific theories, 63, 218.