Cosmos, Vol. 5

when he expressed in a preface "that metaphysical natural science lasts no longer than where mathematics can be combined with metaphysical propositions." A thinker long friendly to me and passionately devoted to Kantian views, Jacob Friedrich Fries, felt compelled to declare at the conclusion of his History of Philosophy: "that of the admirable progress which the study of nature has made up to the year 1840, everything belongs to observation and the art of geometry, the art of mathematical analysis; natural philosophy Naturphilosophie: a movement in German idealism that sought to understand nature through speculative reasoning rather than just empirical data. has contributed nothing at all to these discoveries." May a testimony of past fruitfulness not destroy all hope for the future! For it does not befit the free spirit of our time to reject every philosophical attempt—founded simultaneously on induction and analogies—to penetrate deeper into the chaining of natural phenomena as a baseless hypothesis; nor does it befit us to condemn those noble faculties with which nature has endowed man: now the reason, brooding over the causal connection Causalzusammenhang: the interconnected web of cause and effect that governs the universe.; now the active imagination, necessary and stimulating for all discovery and creation.⁶

I, for my part, believe I have accomplished what I could set out to undertake according to the nature of my inclinations and the measure of my powers. I wished to provide a work following the great model of the Exposition of the System of the World original: "Exposition du Système du Monde" by Laplace, in whose stimulating proximity I had the good fortune to live for over twenty years in Arcueil and at the Bureau of Longitudes at the Paris Observatory, with Gay-Lussac and Arago. If even in the Mechanics of the Heavens, despite the simplicity of the acting forces, we find in many states of the being of celestial bodies