Generelle Morphologie was not only a rallying call for the new theory of evolution but also the book in which Haeckel first named Humboldt’s discipline: Oecologie, or ‘ecology’. Haeckel took the Greek word for household – oikos – and applied it to the natural world. All the earth’s organisms belonged together like a family occupying a dwelling; and like the members of a household they could conflict with, or assist, one another. Organic and inorganic nature made a ‘system of active forces’, he wrote in Generelle Morphologie, using Humboldt’s exact words.
