Knowledge, aim of, 19; individual, compared to telephone, 7 ff.; limited, 31; possibility of error in, ineradicable, 40; social character of, 183 Language, beginnings of, 88; defective in co-ordination, 96; distinction between science and knowledge of, 98; good usage in, 100; and intercourse, 182 ff.; needless inflections in, 99 ff.; of words more imperfect than written language, 92; purpose of its cultivation, 99; the science of, 97 ff.; unambiguity the ideal of, 89; a universal auxiliary, 100; written, 89 ff. Leibnitz, 88; his doctrine of pre-established harmony, 143; inventor of differentials, 112 Life, 163 ff.; the most general concept in the biological sciences, 56 Light, 5, 156 ff. Liquids, 145 Locke, John, 21 ff., 88; his elaboration of the notion of simple and complex "ideas," 21; his secondary qualities, 127 Logic, 54, 67 ff.; content of, 19; definition of, 15 ff. Luther, 99 Magnetism, electricity and, 154 ff. Man, compared to pair of sieves, 34; his capacity for perfection, 180 Manifold, the science of the, 54 Mass, 132 ff., 136 ff.; a substance, 138 Mathematical laws, accuracy of, 105 Mathematics, 54; an empirical science, 55; influence on, of concept of continuity, 111; its progress after introduction of Indo-Arabic numerals and algebraic signs, 101 Matter, definition of, 138 Mayer, Julius Robert, 149; his discovery of the law of conservation, 151 Measurement, 107 Mechanical energies, 144 Mechanics, 55, 128 ff.; complementary branches of, 144 ff.; definition of, 138; early development of, 139; energetic, 138 ff.; the first branch of physics treated mathematically, 139; pure or classical, 144 Mechanistic hypothesis, the, as an interpretation of all natural phenomena, 142; especially injurious in study of mental phenomena, 142 Mechanistic theories, 140 ff. Mechanistic theory of the universe, 132 Mechanization of astronomy, 141 Memory, 16, 32, 180; definition of, 172; general characteristic of, 61; lack of, in inorganic world, 53 Metabolism, 165 Methodology of the sciences based upon co-ordination, 85 Microscope, 6 Motion, the science of, 54, 122; uninfluenced, 122 Musical notation, 93 Names, arbitrariness of, 62; signs and, 86 ff. Natural laws, 28 ff.; definition of, 28; their extent dependent upon stage of knowledge in each science, 7; their usual origin, 42 ff.; prediction from, only approximate, 48 Natural philosophy, definition of, 1; importance of, in study of science, 10; place of, in text-books, 9 ff. Negation, 68 ff. Nerves, 177 Nervous discharge, 177 Newton, Sir Isaac, 141 Number groups, unlimited, 78 Numbers, 78 ff.; theory of, 80 Numerals, co-ordination of, with signs, 86