Who was this «German Darwin», the scholar whom particularly conservative circles and the Catholic Church criticized for his evolutionary theory and insulted as the «Ape Professor»? The man who coined the term Oecologie in 1866? Due to whom biology lessons were altogether banned by law from classrooms in Prussia? Who was proclaimed «antipope» at an international congress of freethinkers in Rome in 1904? Who wrote in Magnus Hirschfeld’s magazine for sexology about human hermaphrodites? Whose ideas even left-wing circles were interested in, but whose writings on «eugenics» and »racial hygiene» were later appropriated by the Nazis, and who posthumously became a progressive inspiration for «real existing socialism» in the German Democratic Republic?

Beauty and Nature

Kunstformen der Natur (Art Forms of Nature) was published at the end of the 19^th century and became a staple book for educated bourgeois households. Haeckel’s drawings of tiny plankton organisms are simply ravishing in their enchanting beauty, their detailed precision, and their fascinating symmetry. Haeckel had discovered over 100 different radiolaria (marine protozoa), which immediately found a large audience at the time and even influenced directly René Binet’s Porte monumentale at the 1900 Paris World Exhibition. 

It was the age of Art Nouveau, with its characteristic vegetal and floral elements finding their way into international design, and the organic world hooking up with the mechanical world. Haeckel understood like few other scientists how to create a synthesis between art and science, and he remained committed to both fields throughout his life. We owe him wonderful marine biology drawings of medusae, sea anemones, and many other life forms from the world of the oceans.

Haeckel made otherwise inaccessible phenomena visible to us by way of scientifically meticulous reproduction. This was only one possibility among a number of approaches—it is ultimately up to the subjective decision of the scientists how to present and illustrate their discoveries. Just take today’s colorful astronomical clouds and bolts of lightning, which present the universe to us in an almost astrological manner, visually already providing a certain interpretation.

Supporting the theory of evolution

As a scientist, Haeckel postulated in 1868 the common origin of all organisms from protozoa and explained Darwin’s essential statements on the theory of common descent in his Natürliche Schöpfungsgeschichte (The History of Creation). He extended the theory of evolution to humans and promoted in 1847 the descent of prehistoric humans from apes—a move that reactionary circles and, unsurprisingly, the Roman Catholic Church never forgave him: they subsequently nicknamed him the «Ape Professor of Jena». Finally in 1866, in his Generelle Morphologie der Tiere (General Morphology of Organisms), he coined the term ‘ecology’ (Oecologie) as the science of the relations between organisms and the environment. 

His 1899 book Die Welträtsel: Gemeinverständliche Studie über monistische Philosophie (The Riddle of the Universe at the Close of the Nineteenth Century) quickly reached a circulation of several hundred thousand copies, making it by far the biggest popular scientific success in the history of German books. The Riddle of the Universe leveraged the breakthrough of the Darwinian theory of evolution, which then met with broader social acceptance for the first time. The monism advocated by Haeckel stands for a synthesis of the organic and the inorganic world, for the subordination of humans to nature, and is directed against the prevailing dualism of mind versus matter.

Haeckel not only presents the state of contemporary scientific research, but also undertakes an ideological and philosophical interpretation. As well he tackles Catholicism. Due to its veneration of a multitude of saints, he refers to «Catholic polytheism» as a «miserable caricature of Christian monotheism», and explicitly denounces the crimes committed by the church and its brutal suppression of the sciences. Just as a reminder: after the Vatican`s dogma of the Immaculate Conception (in 1854!), the papal encyclical Quanta Cura was issued along with the Syllabus Errorum in 1864, effectively denying science any independent activity. To replace Christianity, Haeckel proposed «our monistic religion» with its deities Truth, Beauty, and Virtue: values known from Greek antiquity. Nature itself would be the church of this monistic religion.

There are also several rather ethereal considerations pertaining to the «ether» itself as positive, imponderable matter of the universe. And the following, thoroughly beguiling thought that the «most wondrous of all natural phenomena that we usually designate by the word ‹spirit› or ‹soul›, is a general property of living things … we must rather suppose that the primal elements of soul-life, the simple forms of sensibility, pleasure and pain, the simple forms of motion, attraction and repulsion, are in all living matter, in all protoplasm».