Labels, the value of, 201. Labor, the accumulation of, the foundation of wealth and power, 198; inquirer's division of, 105, 258. Labyrinth, of the ear, 18, 291, 305. Lactantius, on the study of moral and physical science, 89. Ladder of our abstraction, the, 208. Ladies, their eyes, 71; like tuning-forks, 23-24. Lagrange, on Huygens's principle, 149; on the principle of virtual velocities, 150-155; character of the intellectual activity of a, 195, 278. Lake-dwellers, 46, 271. Lamp-shade, 70. Lane's unit jar, 115. Language, knowledge of the nature of, demanded by a liberal education, 356; relationship between, and thought, 358; communication by 237; economy of, 191 et seq.; human its character, 238; of animals, 238; instruction in, 338 et seq.; its methods, 192. Laplace, on the atoms of the brain, 188; on the scientific achievements of the eighteenth century, 188; his hypothesis of the origin of the planetary system, 5. Latent heat, 167, 178, 244. Latin city of Maupertuis, 339. Latin, instruction in, 311 et seq.; introduced with the Christian Church, 340; the language of scholars, the medium of international intercourse, its power, utility, and final abandonment, 341-347; the wealth of its literature, 348; the excessive study of, 346, 349, 354, 355; its power to sharpen the judgment, 357-358. Lavish extravagance of science, 189. Law, a, defined, 256; a natural, not contained in the conformity of the energies, 175. Law-maker, motives of not always discernible, 9. Layard, 79. Learning, its nature, 366 et seq. Least superficial area, principle of, accounted for by the mutual attractions of liquid particles, 13-14; illustrated by a pulley arrangement, 12-13; also 9 et seq. Leibnitz, on harmony, 33; on international intercourse, 342, footnote. Lessing, quotation from, 47. Letters of the alphabet, their symmetry, 94, 97. Level heights of work, 172-174. Lever, a, in action, 222. Leverrier, prediction of the planet Neptune, 29. Leyden jar, 114. Liberal education, a, 341 et seq., 359, 371. Libraries, thoughts stored up in, 237. Lichtenberg, on instruction, 276, 370. Licius, a Chinese philosopher, 213. Liebig, 163, 278. Life and death, 186. Light, history of as elucidating how theories obstruct research, 242; Huygens's and Newton's views of, 227-228; its different conceptions, 226; rectilinear propagation of, 194; rôle of, in vision, 81; spatial and temporal periodicity of, explains optical phenomena, 194; numerical velocity of, 58; where does it go to? 199; generally, 48 et seq. Like effects in like circumstances, 199. Likeness, 388, 391. Lilliput, 84. Lines, straight, their symmetry, 98; curved, their asymmetry, 98; of force, 249. Links of thought, intermediate, 198.