Cosmos, Vol. 4

The relationship between attraction—as a cause of perpetual motion on the surface of the Earth, and most likely in its interior—and the attraction of gravitation, which moves the planets as well as their central bodies just as perpetually, remains completely unknown to us. Even a partial solution to such a purely physical problem would represent the highest and most glorious achievement that experiment and the connection of ideas could possibly reach through these paths. In the contrast just mentioned, I do not like to refer to the attraction that governs the celestial spaces across boundless distances, and which behaves inversely as the square of the distance, exclusively as "Newtonian," as is commonly done. Such a designation contains almost an injustice toward the memory of that great man, who already recognized both manifestations of force The author refers to the distinction between large-scale gravity and molecular-scale forces like cohesion., yet by no means separated them so sharply that he did not attempt—as if in a fortunate premonition of future discoveries—to ascribe capillarity capillarity: the ability of a liquid to flow in narrow spaces without the assistance of external forces and the little that was then known of chemical affinity to universal gravitation in his additions to the Optics. (Laplace, Exposition of the System of the World p. 384; Cosmos Vol. III. p. 22 and 32 note 39.)

Just as in the world of the senses, mirages primarily dawn upon the horizon of the sea, promising the expectant discoverer the possession of a new land for a time; so too on the ideal horizon in the most distant regions of the world of thought, many promising hopes have risen for the earnest researcher and disappeared again. To be sure, the magnificent discoveries of recent times have been suited to increase this tension: such as contact electricity original: "Contact-Electricität"; refers to the then-emerging study of electrochemical cells and the voltaic pile;