In the first half of the nineteenth century, there were strong elements in German intellectual life, stemming from the cultural tradition of classicism and the philosophical one of idealism, arguing in favor of the unity of all systematic knowledge. Probably the most prominent proponent of such ideas was the philosopher G.W.F. Hegel (1770-1831). His 1817 Encyclopedia of the Philosophical Sciences, an excerpt from which is provided here, was a sort of brief account of the unity of such knowledge. Hegel's convoluted prose is notoriously difficult to understand, but the student might want to note Hegel's argument that philosophy – because it addresses the creation and definition of concepts – is the master branch of knowledge. Hegel developed basic ideas of physics and biology from philosophical concepts and was not afraid to criticize Isaac Newton's theories of physics on the basis of his philosophy.
Hegel included what we would now call the humanities and social sciences in his unity of all knowledge. In the following excerpt from his lectures on the philosophy of world history, delivered during the 1820s when he was a professor at the University of Berlin, Hegel explains that the meaning of human history is the progress of the philosophical concept of freedom.
Alexander von Humboldt (1769-1858) was a naturalist and explorer, whose celebrated expedition to South America, lasting from 1799 to 1804, generated a lifetime of scholarly studies of botany and natural history. Toward the end of his life, between 1845 and 1858, Humboldt wrote the multi-volume work Cosmos, in which he attempted to articulate the unity of all scientific and scholarly knowledge, demonstrating its links to human passions and desires, and to practical engineering and economics as well.
Humboldt's attempt to articulate the unity of knowledge was one of the last examples of such a classicist and idealist effort. As early as the 1820s a quite different attitude was appearing – one that would become dominant among German scholars and scientists after the middle of the nineteenth century. In an 1862 speech given upon his appointment as pro-rector at the University of Heidelberg, the physicist Hermann von Helmholtz (1821-94), formulator of the law of the conservation of energy, explicitly rejected Hegel's ideal of a philosophical unity of knowledge. Rather, he drew clear conceptual and epistemological distinctions between the natural and physical sciences on the one hand, and the humanities and social sciences on the other.