Numerical names different in different languages, 86 Numerical signs international, 86 Nutrition, 165 Objective, astronomic, 6; photographic, 6 Objective character of the world, 34 Optical telegraph, 90 Optics, geometric, 5 Optic signs, 90 Order, most general concept in formal sciences, 56 Organisms, standard for measuring relative perfection of, 176; stationary forms, 163 Orthography, efforts to improve, 99; English, defective in co-ordination, 96; exaggerated importance of correctness in, 99; mistakes in, 97; reform of, 97 Parabolic curve, 48 Paradoxes of the infinite, 84 Pasigraphy, 92 ff.; Chinese system of, 94 Permanent in change, the, 131 Perpetual motion, 130 Perpetual motion machine, 153 Philology, 97 ff. Philosophy, limited progress in, 101 Phonetic writing, 33 ff. Phoronomy, 54, 119, 122, 127 Photochemical processes, foundation of terrestial life, 169 Photographic objective, 6 Physical sciences, 55 Physics, 47, 55; each branch of, treats of a special kind of energy, 139 the science of the different kinds of energy, 72; Physiology, 55 ff. Plato, his distinction between mental and physical life, 178 Polarity of electricity and magnetism, 155 Political organizations, conflicts between, 185 Prediction, 12 Pre-established harmony, 143 Pressure, 146, 154 Progress, depends on collective labor, 185; economy of energy, 184; evaluation of, 176 Pseudo-problems in science, 142 Psychology, 47, 55 ff. Psycho-physical parallelism, 143 Ptolemy's system, 117 Pure science, 57 Quantity, the science of, see Mathematics, 54 Radiant energy, 157; its importance to man, 158 Rational sciences, see Deductive sciences Rays, straight lines of, 5 Reaction, teleological, 173 Reality, 16 ff. Reflection, 5 Reflex action, 173 Refraction, 5 Repetition, basis of conscious life, 174 Reproduction, 165 ff. Roman notation, 91 Science, aim of, 13 ff.; comparison of, to a network, 42; comparison of, to a tree or forest, 6; definition of, 13; eternal truth of, 6 ff.; "for its own sake," 13 ff.; the facts of, unalterable, 8 ff.; the function of, 23, 37; importance of theoretical, 15; its procedure, 45; the study of happiness, 28 Sciences, the table of the, 54 ff. Scientific discoveries, independent simultaneous, 185 Scientific instinct, 43 Scientific materialism, 138 Scientific written language based on direct co-ordination, 93 Self-preservation, 180 Sense organs, 176 ff. Shakespeare, 99 Signs and names, 86 ff. Social characteristics, importance of, 179 ff. Social classes, conflicts between, 185 Socialization of human capacities, 180 Social order still barbarous, 185