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 EIGHTH BOOK.

The romantic philosophy believed it could reform natural science. And this notwithstanding the fact that at the very time of the origin of this philosophy, the closing decades of the eighteenth century, natural science was making astounding progress. The traditional conviction of the persistence of matter throughout all changes was experimentally demonstrated by Lavoisier, by means of the quantitative method,—by weighing,—and the fundamental laws governing the material changes involved in the constitution of plant and animal life were discovered by a number of investigators (Priestley, Saussure, etc.), and organic life was thus incorporated within the majestic cycle of material processes.

Natural science received a new impetus during the forties of the nineteenth century, due especially to Robert Mayer's discovery of the principle of the conservation of energy (1842). Ideas which had already been suggested by Descartes, Huyghens and Leibnitz now received their empirical authentication, because the demonstration that there is no dissipation of force, already established in pure mechanics, could likewise be demonstrated in the interaction of the particular forces of nature, because it could be shown that a definite quantitative relation exists between the potential value (e. g. motion) which vanishes and the new potential value (e. g. heat) which arises.

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