Energy, a substance, 136; at rest, 154; free, 154; importance of concept of, 128; in nerves, 177; the most general concept in the physical sciences, 56; of form, 145; of volume, 145 Energy intensity, 153 Erg, definition of, 150 Esperanto, 183, note Euclid, 44, 140 European-American scripts based on indirect co-ordination, 93 Experience, incompleteness of, 27; more limited than the conceivable, 118 Experiences, distinguished by _being familiar_, 31; limited knowledge of, 31 Experiential sciences, see Empirical sciences Extrapolation, 46, 50, 104 Familiarity due to recalling former similar experiences, 11 Fechner, 102 Feeling, thinking, acting, 174 ff. Force, 129 ff., 153 Formal sciences, 54; are empirical sciences, 55; order most general concept in, 56 Foucault's pendulum experiment, 121 Freedom of the will, 50 ff. Frequency of process facilitates repetition, 11 ff. Function, 109 ff.; continuous and discontinuous, 110; most general concept in formal sciences, 56 Functional relation, the application of the, 112 ff. Functions, the theory of, 111 Fundamental principle, the second, 150 ff. Gases, 145 Generalization, suitable place for, in text-books, 9 ff. Geometry, 47, 54, 119, 127; ancient and modern methods of, 110 ff. Goethe, 99 Good usage in language, 100 Grammatical correctness, importance attached to, 99 Grammatical rules, 97 Gravitation potential, the, 112 Group, the, 65 ff.; double members or double points in, 82; linear arrangement of members of, 75 ff. Groups, artificial and natural, 69 ff.; closed, among animals, 179; infinite, equality of, 84; related, 69 ff.; unequivocal order of, 83 Heat, mechanical equivalent of, 149; theory of, 147 ff. Heat energy, 148 ff. Heat engine, 151; ideal, 151 ff. Heat quantity, 148 ff. Heliotrope, 90 Herbart, 102 Heredity, 180 Higher analysis, 111 Homonym, 89 Hydromechanics, 147 Ideal cases, 44 ff. Ideal machines, 132 Identity, the limit case in co-ordination, 82 Ido, 183, note Imperfection, indestructible quality of science, 4 Incompleteness, no hindrance to efficiency of science, 5 Indestructibility of matter, see Conservation of matter Indo-Arabic notation, 91 Induction, 38; the complete and the incomplete, 39 Inductive sciences, 38 Inference, by induction, 38; from analogy, 140 Infinitesimal analysis, 111 Inorganic world, lack of memory and foresight in, 33 Insoluble problems, 142 Instinctive action, 174 Intercourse, language and, 182 ff. Isolation among plants and animals, 179 Isomeric, 74 Isomeric changes, 161 Judgments, analytic, 66 Kant, 44, 66, 105 Kepler, 141 Kinetic energy, 132; and work, their sum constant, 133 ff.; transformed into work and _vice versa_, 134