“First, In showing in how to avoid attempting impossibilities.
Second, In securing us from important mistakes in attempting what is, in itself possible, by means either inadequate or actually opposed to the end in view.
Thirdly, In enabling us to accomplish our ends in the easiest, shortest, most economical, and most effectual manner.
Fourth, In inducing us to attempt, and enabling us to accomplish, object which, but for such knowledge, we should never have thought of understanding.”

“The sun's rays are the ultimate source of almost every motion which takes place on the surface of the earth. By their heat are produced all winds, and those disturbances in the electric equilibrium of the atmosphere which give rise to the phenomena of terrestrial magnetism. By their vivifying action vegetables are elaborated from inorganic matter, and become in their turn the support of animals and of man, and the sources of those great deposits of dynamical efficiency which are laid up for human use in our coal strata. By them the waters of the sea are made to circulate in vapor through the air, and irrigate the land, producing springs and rivers. By them are produced all disturbances of the chemical equilibrium of the elements of nature which, by a series of compositions and decompositions, give rise to new products, and originate a transfer of materials. Even the slow degradation of the solid constituents of the surface, in which its chief geological changes consist, and their diffusion among the waters of the ocean, are entirely due to the abrasion of the wind, rain, and tides, which latter, however, are only in part the effect of solar influence and the alternate action of the seasons.”

“A mind which has a taste for scientific inquiry, and has learned the habit of applying its principles readily to the cases which occur, has within itself an inexhaustable source of pure and exciting contemplations. One would think that Shakespeare had such a mind in view when he describes a contemplative man as finding—
      'Tongues in trees, books in running brooks,
      Sermons in stones, and good in everything,'
   Accustomed to trace the operations of general causes and the exemplification of general laws, in circumstances where the uninformed and uninquiring eye, perceives neither novelty nor beauty, he walks in the midst of wonders ; every object which falls in his way elucidates some principle, affords some instruction and impresses him with a sense of harmony and order. Nor is it a mere passive pleasure which is thus communicated. A thousand questions are continually arising in his mind, a thousand objects of inquiry presenting themselves, which keep his faculties in constant exercise and his thoughts perpetually on the wing, so that lassitude is excluded from his life, and that craving after artificial excitement and dissipation of the mind which leads so many into frivolous, unworthy and destructive pursuits, is altogether eradicated from his bosom.”