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Riddle of the Universe
Greatly influenced by Charles Darwin, the famed German zoologist and philosopher Ernst Haeckel (1834-1919) boldly defended the fact of organic evolution and seriously considered its far-reaching ramifications for science, philosophy, and theology. Advocating the interplay of empirical evidence and rational speculation, The Riddle of the Universe is his most daring, comprehensive, and successful work. Its monistic and naturalistic worldview offers a cosmic perspective and evolutionary framework that supplants traditional theistic beliefs in God, free will, and the personal immortality of the human soul. This classic volume remains a tour de force of critical thought, free inquiry, and intellectual value.
- GenresPhilosophyScienceGermany
405 pages, Paperback
First published January 1, 1899
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441 people want to read
About the author
Ernst Haeckel
912 books127 followersErnst Heinrich Philipp August Haeckel (February 16, 1834 – August 9, 1919), also written von Haeckel, was an eminent German biologist, naturalist, philosopher, physician, professor and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology, including anthropogeny, ecology, phylum, phylogeny, stem cell, and the kingdom Protista. Haeckel promoted and popularized Charles Darwin's work in Germany and developed the controversial recapitulation theory ("ontogeny recapitulates phylogeny") claiming that an individual organism's biological development, or ontogeny, parallels and summarizes its species' evolutionary development, or phylogeny.
The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures (see: Kunstformen der Natur, "Art Forms of Nature"). As a philosopher, Ernst Haeckel wrote Die Welträtsel (1895–1899, in English, The Riddle of the Universe, 1901), the genesis for the term "world riddle" (Welträtsel); and Freedom in Science and Teaching to support teaching evolution.
The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures (see: Kunstformen der Natur, "Art Forms of Nature"). As a philosopher, Ernst Haeckel wrote Die Welträtsel (1895–1899, in English, The Riddle of the Universe, 1901), the genesis for the term "world riddle" (Welträtsel); and Freedom in Science and Teaching to support teaching evolution.
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Displaying 1 - 6 of 6 reviews
April 3, 2021
I personally was shocked how accurate his worldview was, compare his worldview to his contemporaries (e.g the fundamentals, spiritualists) and it's shockingly accurate. Intellectual progess has largely held up his conclusions.
And he argues for non-theism much better then so many modern books (don't get me started on the "new atheist"), a lot of his framing is better then contemporary philosopical framing, I much prefer his term of "thanatism" and "athanatism" compared to "mortalist" and "survivalist".
In regards to him being a supposed "ebil racist nazi", this is a connotation literally every famous German from the early 20th and late 19th century gets. This is based on bogus early post war scholarship that was trying to build grand narratives about Nazi Germany, usually tied to this idea of the sonderweg (special way). Examples of this include german empire having a welfare state or compulsory education, and this somehow means that nazism was right around the track. Also the constant fear-mongering that evolutionary biologist is just a polite way to say racist and a nazi. If you search the monisitic league in german google brings no connotation to nazism. Because it is obviously false if you have the primary sources. Richard Jacques, historian of biology, wrote a good book on Haeckel that debunks these bogus claims.
Yes the Monistic league had ideological nazis, it also had trans right's activist. It was ideologically diverse movement just like modern groups and organizations.
And he argues for non-theism much better then so many modern books (don't get me started on the "new atheist"), a lot of his framing is better then contemporary philosopical framing, I much prefer his term of "thanatism" and "athanatism" compared to "mortalist" and "survivalist".
In regards to him being a supposed "ebil racist nazi", this is a connotation literally every famous German from the early 20th and late 19th century gets. This is based on bogus early post war scholarship that was trying to build grand narratives about Nazi Germany, usually tied to this idea of the sonderweg (special way). Examples of this include german empire having a welfare state or compulsory education, and this somehow means that nazism was right around the track. Also the constant fear-mongering that evolutionary biologist is just a polite way to say racist and a nazi. If you search the monisitic league in german google brings no connotation to nazism. Because it is obviously false if you have the primary sources. Richard Jacques, historian of biology, wrote a good book on Haeckel that debunks these bogus claims.
Yes the Monistic league had ideological nazis, it also had trans right's activist. It was ideologically diverse movement just like modern groups and organizations.
June 29, 2025
Ernst Haeckel’s The Riddle of the Universe (Die Welträthsel), first published in 1899, stands as a foundational work in the popularization of monistic philosophy and the scientific worldview at the turn of the twentieth century. Positioned at the intersection of natural science, metaphysics, and cultural polemic, the book endeavors to articulate a comprehensive worldview grounded in Darwinian evolutionary theory, materialism, and a radical rejection of dualism. Haeckel’s sweeping synthesis of biology, cosmology, and philosophical anthropology has proven historically influential and continues to invite critical reflection for its bold conflation of science and metaphysical assertion.
Haeckel, a leading German zoologist and early disciple of Charles Darwin, presents The Riddle of the Universe as a “monistic confession of faith.” His principal argument rests on the assertion that all phenomena, from cosmic evolution to human consciousness, are reducible to physical processes governed by immutable natural laws. For Haeckel, dualistic conceptions that posit separations between mind and body, matter and spirit, or God and nature are not only untenable but obstruct scientific and cultural progress. He proclaims a worldview in which materialism and evolution explain not only biological development but also the emergence of reason, ethics, and art.
Structured in twenty chapters, the book systematically addresses what Haeckel sees as the central problems of philosophy—the origin of matter, the nature of life, the evolution of species, the emergence of consciousness, and the fate of the soul. His discussions draw heavily on contemporary scientific knowledge in embryology, comparative anatomy, and geology, but also stretch into speculative terrain, particularly in his treatment of consciousness and the mind-body problem. Haeckel adopts a strong form of psychophysical parallelism, asserting that mental and physical processes are two aspects of the same reality, though he ultimately privileges the material basis of mind.
One of the defining features of the text is its polemical tone. Haeckel writes not only as a scientist but as a cultural reformer, castigating the Catholic Church, metaphysical idealism, and what he saw as the obscurantist tendencies of contemporary philosophy. He reserves particular scorn for Kantian agnosticism and the doctrine that ultimate realities are unknowable. In its place, Haeckel asserts that the scientific method, bolstered by Darwinian theory, can and must address the fundamental riddles that philosophers have traditionally claimed as their own.
The strengths of The Riddle of the Universe lie in its intellectual ambition and clarity of exposition. Haeckel communicates complex scientific ideas in accessible prose, which undoubtedly contributed to the book’s wide readership across Europe and America. Moreover, his vision of science as a unifying, world-explaining force resonated with fin-de-siècle hopes for a comprehensive, secular modernity.
However, the book is not without significant limitations. Haeckel’s reductionist tendencies frequently lead him to dismiss complex philosophical and theological positions with insufficient engagement. His treatment of mind and consciousness, while grounded in the scientific context of his time, now appears naïvely deterministic. Moreover, critics have noted the political and ethical implications of his monism, particularly in the context of later movements in German intellectual history that co-opted aspects of his evolutionary views. Indeed, the book’s deterministic overtones and biologistic rhetoric raise enduring questions about the dangers of conflating scientific explanation with normative judgment.
The Riddle of the Universe is a landmark in the history of scientific materialism and evolutionary thought. It encapsulates the aspirations and limitations of a worldview that seeks to resolve philosophical questions through empirical science alone. While modern developments in neuroscience, quantum theory, and philosophy of mind have superseded many of Haeckel’s conclusions, his work remains a compelling document of a pivotal moment in the cultural and intellectual evolution of modern Europe. As such, it deserves continued study—not only for its scientific and philosophical content, but also for the light it sheds on the cultural dynamics of secular modernity.
GPT
Haeckel, a leading German zoologist and early disciple of Charles Darwin, presents The Riddle of the Universe as a “monistic confession of faith.” His principal argument rests on the assertion that all phenomena, from cosmic evolution to human consciousness, are reducible to physical processes governed by immutable natural laws. For Haeckel, dualistic conceptions that posit separations between mind and body, matter and spirit, or God and nature are not only untenable but obstruct scientific and cultural progress. He proclaims a worldview in which materialism and evolution explain not only biological development but also the emergence of reason, ethics, and art.
Structured in twenty chapters, the book systematically addresses what Haeckel sees as the central problems of philosophy—the origin of matter, the nature of life, the evolution of species, the emergence of consciousness, and the fate of the soul. His discussions draw heavily on contemporary scientific knowledge in embryology, comparative anatomy, and geology, but also stretch into speculative terrain, particularly in his treatment of consciousness and the mind-body problem. Haeckel adopts a strong form of psychophysical parallelism, asserting that mental and physical processes are two aspects of the same reality, though he ultimately privileges the material basis of mind.
One of the defining features of the text is its polemical tone. Haeckel writes not only as a scientist but as a cultural reformer, castigating the Catholic Church, metaphysical idealism, and what he saw as the obscurantist tendencies of contemporary philosophy. He reserves particular scorn for Kantian agnosticism and the doctrine that ultimate realities are unknowable. In its place, Haeckel asserts that the scientific method, bolstered by Darwinian theory, can and must address the fundamental riddles that philosophers have traditionally claimed as their own.
The strengths of The Riddle of the Universe lie in its intellectual ambition and clarity of exposition. Haeckel communicates complex scientific ideas in accessible prose, which undoubtedly contributed to the book’s wide readership across Europe and America. Moreover, his vision of science as a unifying, world-explaining force resonated with fin-de-siècle hopes for a comprehensive, secular modernity.
However, the book is not without significant limitations. Haeckel’s reductionist tendencies frequently lead him to dismiss complex philosophical and theological positions with insufficient engagement. His treatment of mind and consciousness, while grounded in the scientific context of his time, now appears naïvely deterministic. Moreover, critics have noted the political and ethical implications of his monism, particularly in the context of later movements in German intellectual history that co-opted aspects of his evolutionary views. Indeed, the book’s deterministic overtones and biologistic rhetoric raise enduring questions about the dangers of conflating scientific explanation with normative judgment.
The Riddle of the Universe is a landmark in the history of scientific materialism and evolutionary thought. It encapsulates the aspirations and limitations of a worldview that seeks to resolve philosophical questions through empirical science alone. While modern developments in neuroscience, quantum theory, and philosophy of mind have superseded many of Haeckel’s conclusions, his work remains a compelling document of a pivotal moment in the cultural and intellectual evolution of modern Europe. As such, it deserves continued study—not only for its scientific and philosophical content, but also for the light it sheds on the cultural dynamics of secular modernity.
GPT
November 21, 2019
Haeckel's philosophy of monism is elaborated on brilliantly.
Whether the soul is one with the body or separated as in dualism is discussed at length . God is all and everywhere not on some unseen seat stroking his beard and passing judgment on everything as some Christians truly believe.
A long diatribe against catholicism and rightly so for being the instigator of the dark ages temporarily killing science and making arbitrary decisions like the immaculate conception and the retrospective infallibility of all popes though early Christianity pre Nicene congress is praised as its purest form and truer to Christ's teachings.
A great read which created quite a stir when first released.
Whether the soul is one with the body or separated as in dualism is discussed at length . God is all and everywhere not on some unseen seat stroking his beard and passing judgment on everything as some Christians truly believe.
A long diatribe against catholicism and rightly so for being the instigator of the dark ages temporarily killing science and making arbitrary decisions like the immaculate conception and the retrospective infallibility of all popes though early Christianity pre Nicene congress is praised as its purest form and truer to Christ's teachings.
A great read which created quite a stir when first released.
December 5, 2025
The riddle of the universe actually refers to seven scientific riddles from an 1880 speech at the Berlin academy of sciences:
1 nature of matter and force
2 origin of motion
3 origin of life
4 orderly arrangement of nature
5 origin of simple sensation and consciousness
6 rational thought, origin of speech
7 freedom of the will
To which Haeckel throughout the book addresses:
1,2,5 are answered by conception of substance (conservation)
3,4,6 by evolution
7 is an illusion
Haeckel’s monism was an evolutionary update to Spinoza’s pantheism given the progress of Newtonian mechanics, thermodynamics, and Darwinian evolution of which Haeckel was an aggressive proponent to a German audience. Monism was premised on the law of substance (conservation) that everything is made of the same material and under certain conditions can become everything else which presages mass energy equivalence, and a law of causality which means that everything is subject to the same laws (determinism) and so everything interacts with everything else (evolution).
Haeckel’s monism actually went further than Spinoza, as he did not identify mind with matter but that mind and body are only two attributes of the one substance, god, who has infinite attributes. Haeckel’s view is closer to materialism but that matter is capable of consciousness which is related to panpsychism or hylozoism, consciousness or life is an inherent property of matter. I think you can update his monism with panprotopsychism, that matter is potentially conscious in certain configurations according to the rules of computation and cosmologically with the anthropic principle that the evolution of intelligent life is the purpose of the universe, understood by Kurzweil’s singularity and Tipler’s omega point. This gets away from Haeckel’s purely secular naturalist intentions back to a position more reconcilable with theism though.
The book is about half history of science up the nineteenth century and the rest describing the tenets of monism as adapting polyphyletic truths found in religion while discarding their supernatural tenets. Compared to the cautious Darwin Haeckel was bold enough to publicly challenge traditional and religious assumptions and propose effectively a secular religion. Haeckel attributed monotheism to solar worship and anthropomorphism from mind-body dualism and his own monism to worship of the entirety of nature including humanity. The most controversial content are Haeckel’s anti-Christian passages about the Nicene creed being selected according to a miracle (citing the dubious Synodicon of Pappus) which I believe was popularized by Voltaire, Jesus having a Roman father Pandera attributed to the Talmud and pagan critic Celsus, and even that the trinity is tritheistic given its personal nature. Much of this reflects the anti-clerical kulturkampf and higher biblical criticism among German intellectuals which was also influenced by Spinoza.
As to positive content Haeckel’s monism adapts the morality of the golden rule found not only in christianity but also loosely in Confucius, Aristotle and Pittacus of Mylene. Monist ethics is against the categorical imperative’s dualism between self-interest and society, aiming to unite egoism and altruism in the manner of fellow evolutionist Herbert Spencer’s utilitarianism. Still here is criticism of Christian attitudes against the self, the body, nature, family, and women which I see more as an gnostic asceticism than Christian. The monist trinity is Plato’s the true, the good, and the beautiful: truth is the scientific study of nature, good humanist virtues of charity, tolerance, compassion, and assistance which Spinoza summed up as benevolence and justice, and beauty aesthetic pleasure from the study of the forms of nature such as Haeckel’s own Artforms of Nature.
"The equal appreciation of these two natural impulses, or the moral equivalence of self love and love of others, is the chief and fundamental principle of our morality. Hence the highest aim of all ethics is very simple-it is the re establishment of "the natural equality of egoism and altruism, of the love of one's self and the love of one's neighbor." The Golden Rule says: "Do unto others as you would that they should do unto you." From this highest precept of Christianity it follows of itself that we have just as sacred duties towards ourselves as we have towards our fellows."
"The whole of our painting and sculpture, the chief branches of our monistic aesthetics, are intimately blended with Christian, Greek, and Roman mythologies. There will only be this important difference-that the Christian myths and legends will not be taught as truths, but as poetic fancies, like the Greek and Roman myths."
In retrospect Haeckel’s monism was a stripped down unitarianism or Spinozism formatted for late nineteenth century Germany which got associated with the eugenics and national socialist movements, from which Robert Richards defends Haeckel, but gave it a definite black mark alongside Stephen Gould’s criticism of his law of recapitulation which Richards also defends but with modifications, such as the embryo not reflecting adult traits of common ancestors.
I hold Haeckel and Spencer’s cosmologies in high regard but have since beyond materialism and strict naturalism, still their views did influence me towards orthogenetic and teleological views of evolution like that of Teilhard de Chardin which are compatible with theism. Aside from the history of science and ethical and aesthetic content, the rest of the book reads more as a collection of anti-clericalism than a comprehensive treatise, mostly worth it for historical value.
1 nature of matter and force
2 origin of motion
3 origin of life
4 orderly arrangement of nature
5 origin of simple sensation and consciousness
6 rational thought, origin of speech
7 freedom of the will
To which Haeckel throughout the book addresses:
1,2,5 are answered by conception of substance (conservation)
3,4,6 by evolution
7 is an illusion
Haeckel’s monism was an evolutionary update to Spinoza’s pantheism given the progress of Newtonian mechanics, thermodynamics, and Darwinian evolution of which Haeckel was an aggressive proponent to a German audience. Monism was premised on the law of substance (conservation) that everything is made of the same material and under certain conditions can become everything else which presages mass energy equivalence, and a law of causality which means that everything is subject to the same laws (determinism) and so everything interacts with everything else (evolution).
Haeckel’s monism actually went further than Spinoza, as he did not identify mind with matter but that mind and body are only two attributes of the one substance, god, who has infinite attributes. Haeckel’s view is closer to materialism but that matter is capable of consciousness which is related to panpsychism or hylozoism, consciousness or life is an inherent property of matter. I think you can update his monism with panprotopsychism, that matter is potentially conscious in certain configurations according to the rules of computation and cosmologically with the anthropic principle that the evolution of intelligent life is the purpose of the universe, understood by Kurzweil’s singularity and Tipler’s omega point. This gets away from Haeckel’s purely secular naturalist intentions back to a position more reconcilable with theism though.
The book is about half history of science up the nineteenth century and the rest describing the tenets of monism as adapting polyphyletic truths found in religion while discarding their supernatural tenets. Compared to the cautious Darwin Haeckel was bold enough to publicly challenge traditional and religious assumptions and propose effectively a secular religion. Haeckel attributed monotheism to solar worship and anthropomorphism from mind-body dualism and his own monism to worship of the entirety of nature including humanity. The most controversial content are Haeckel’s anti-Christian passages about the Nicene creed being selected according to a miracle (citing the dubious Synodicon of Pappus) which I believe was popularized by Voltaire, Jesus having a Roman father Pandera attributed to the Talmud and pagan critic Celsus, and even that the trinity is tritheistic given its personal nature. Much of this reflects the anti-clerical kulturkampf and higher biblical criticism among German intellectuals which was also influenced by Spinoza.
As to positive content Haeckel’s monism adapts the morality of the golden rule found not only in christianity but also loosely in Confucius, Aristotle and Pittacus of Mylene. Monist ethics is against the categorical imperative’s dualism between self-interest and society, aiming to unite egoism and altruism in the manner of fellow evolutionist Herbert Spencer’s utilitarianism. Still here is criticism of Christian attitudes against the self, the body, nature, family, and women which I see more as an gnostic asceticism than Christian. The monist trinity is Plato’s the true, the good, and the beautiful: truth is the scientific study of nature, good humanist virtues of charity, tolerance, compassion, and assistance which Spinoza summed up as benevolence and justice, and beauty aesthetic pleasure from the study of the forms of nature such as Haeckel’s own Artforms of Nature.
"The equal appreciation of these two natural impulses, or the moral equivalence of self love and love of others, is the chief and fundamental principle of our morality. Hence the highest aim of all ethics is very simple-it is the re establishment of "the natural equality of egoism and altruism, of the love of one's self and the love of one's neighbor." The Golden Rule says: "Do unto others as you would that they should do unto you." From this highest precept of Christianity it follows of itself that we have just as sacred duties towards ourselves as we have towards our fellows."
"The whole of our painting and sculpture, the chief branches of our monistic aesthetics, are intimately blended with Christian, Greek, and Roman mythologies. There will only be this important difference-that the Christian myths and legends will not be taught as truths, but as poetic fancies, like the Greek and Roman myths."
In retrospect Haeckel’s monism was a stripped down unitarianism or Spinozism formatted for late nineteenth century Germany which got associated with the eugenics and national socialist movements, from which Robert Richards defends Haeckel, but gave it a definite black mark alongside Stephen Gould’s criticism of his law of recapitulation which Richards also defends but with modifications, such as the embryo not reflecting adult traits of common ancestors.
I hold Haeckel and Spencer’s cosmologies in high regard but have since beyond materialism and strict naturalism, still their views did influence me towards orthogenetic and teleological views of evolution like that of Teilhard de Chardin which are compatible with theism. Aside from the history of science and ethical and aesthetic content, the rest of the book reads more as a collection of anti-clericalism than a comprehensive treatise, mostly worth it for historical value.
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August 17, 2019Haeckel se propõe a sanar o abismo entre cultura e ciência a partir do desenvolvimento científico no séc. XIX. Abrindo o abismo estão dois continentes culturais/científicos: anthropismo e monismo. O anthropismo vê duas ou mais linhas de causalidade agindo na natureza (Deus, alma e matéria, por exemplo) enquanto que o monismo vê apenas uma, a Substanzgesetz (lei da substância). Assim o mundo é visto por Haeckel. Da unidade fundamental do universal e sua única lei, ele cria uma nova religião que há de sanar a dividida psyquê humana.
Sob a perspectiva de pouco mais de um milênio, vejo que as sementes plantadas por esse livro (à época mais difundido que A Origem das Espécies, sou informado) já frutificam. O ser humano nunca esteve tão em baixa. Movimentos ambientalistas vêm o homem como única/principal causa dos males ao planeta e desejam sua extinção. (o último que encontrei me desaconselhou até a reproduzir em favor das baleias e golfinhos) Também há quem ache que está na hora de passarmos a tocha evolutiva a novos receptáculos, máquinas de I.A. Em produções culturais como "The walking dead" e "blade runner" a humanidade julga difícil se definir diante de, por exemplo, zumbis. Simplismente não há consenso no mainstream cultural se o ser humano per se tem algo de intrinsecamente diferente da natureza.
Embora em essência não seja muito diferente do que dizem, p.ex., Neil de Grasse Tyson e Carl Sagan, as ideias, muito tempo antes propagadas por Haeckel et aliis entraram hoje no sangue de nossa cultura e são relembradas apenas para incentivar o pessoal a estudar ciência.
Sob a perspectiva de pouco mais de um milênio, vejo que as sementes plantadas por esse livro (à época mais difundido que A Origem das Espécies, sou informado) já frutificam. O ser humano nunca esteve tão em baixa. Movimentos ambientalistas vêm o homem como única/principal causa dos males ao planeta e desejam sua extinção. (o último que encontrei me desaconselhou até a reproduzir em favor das baleias e golfinhos) Também há quem ache que está na hora de passarmos a tocha evolutiva a novos receptáculos, máquinas de I.A. Em produções culturais como "The walking dead" e "blade runner" a humanidade julga difícil se definir diante de, por exemplo, zumbis. Simplismente não há consenso no mainstream cultural se o ser humano per se tem algo de intrinsecamente diferente da natureza.
Embora em essência não seja muito diferente do que dizem, p.ex., Neil de Grasse Tyson e Carl Sagan, as ideias, muito tempo antes propagadas por Haeckel et aliis entraram hoje no sangue de nossa cultura e são relembradas apenas para incentivar o pessoal a estudar ciência.
November 11, 2016
Very boring.
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