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
"Nothing is constant but change! All existence is a perpetual flux of "being and becoming"! That is the broad lesson of the evolution of the world... The belief in the freedom of the will is inconsistent with the truth of evolution. Modern philosophy shows clearly that the will is never really free in man or animal, but determined by the organization of the brain; and that in turn acquires its individual character by the laws of heredity and the influence of environment."
"A society for investigating nature and ascertaining truth cannot celebrate its commemoration day more fittingly than by a discussion of its highest general problems."
"All the common phenomena of Morphology and Physiology, of Chorology and ÂŒkology, of Ontology and Paleontology, can be explained by the theory of descent, and referred to simple mechanical causes. It is precisely in this, viz., that the primary simple causes of all these complex aggregates of phenomena are common to them all, and that other mechanical causes for them are unthinkableÂ—it is in this that, to us, the guarantee of their certainty consists."
"An irrefutable proof that such single-celled primaeval animals really existed as the direct ancestors of Man, is furnished according to the fundamental law of biogeny by the fact that the human egg is nothing more than a simple cell."
"As our mother earth is a mere speck in the sunbeam in the illimitable universe, so man himself is but a tiny grain of protoplasm in the perishable framework of organic nature. [This] clearly indicates the true place of man in nature, but it dissipates the prevalent illusion of man's supreme importance and the arrogance with which he sets himself apart from the illimitable universe and exalts himself to the position of its most valuable element."
"Both of these branches of evolutionary science, are, in my opinion, in the closest causal connection; this arises from the reciprocal action of the laws of heredity and adaptation."
"At the lowest stage, the rude--we may say animal--phase of prehistoric primitive man, is the "ape-man," who, in the course of the tertiary period, has only to a limited degree raised himself above his immediate pithecoid ancestors, the anthropoid apes. Next come successive stages of the lowest and simplest kind of culture, such as only the rudest of still existing primitive peoples enable us in some measure to conceive. These "savages" are succeeded by peoples of a low civilization, and from these again, by a long series of intermediate steps, we rise little by little to the more highly civilized nations. To these alone--of the twelve races of mankind only to the Mediterranean and Mongolian--are we indebted for what is usually called "universal history." This last, extending over somewhat less than six thousand years, represents a period of infinitesimal duration in the long millions of years of the organic world's development."
"At the same time, it has to recognize in the shades of difference in form the degree of blood-relationship, and make an effort to construct the ancestral tree of the animal world. In this way, comparative anatomy enters into the closest relations with comparative embryology on the one hand, and with the science of classification on the other."
"Everybody knows that the butterfly emerges from the pupa, and the pupa from a quite different thing called a larva, and the larva from the butterfly's egg."
"But few besides medical men are aware that MAN, in the course of his individual formation, passes through a series of transformations which are not less surprising and wonderful than the familiar metamorphoses of the butterfly."
"Civilization and the life of nations are governed by the same laws as prevail throughout nature and organic life."
"Comparative psychology teaches us to recognize a very long series of successive steps in the development of soul in the animal kingdom. But it is only in the most highly developed vertebrates-birds and mammals--that we discern the first beginnings of reason, the first traces of religious and ethical conduct. In them we find not only the social virtues common to all the higher socially-living animals,--neighborly love, friendship, fidelity, self-sacrifice, etc.,--but also consciousness, sense of duty, and conscience; in relation to man their lord, the same obedience, the same submissiveness, and the same craving for protection, which primitive man in his turn shows towards his "gods.""
"I trust we may be able to arouse the same interest in this delicate field of inquiry as has been excited already in other branches of science; though we shall meet more obstacles here than elsewhere."
"In order to be convinced of this important result, it is above all things necessary to study and compare the mental life of wild savages and of children. At the lowest stage of human mental development are the Australians, some tribes of the Polynesians, and the Bushmen, Hottentots, and some of the Negro tribes."
"In the course of individual development, inherited characters appear, in general, earlier than adaptive ones, and the earlier a certain character appears in ontogeny, the further back must lie in time when it was acquired by its ancestors."
"In many of these languages there are numerals only for one, two, and three: no Australian language counts beyond four. Very many wild tribes can count no further than ten or twenty, whereas some very clever dogs have been made to count up to forty and even beyond sixty."
"In consequence of Darwin's reformed Theory of Descent, we are now in a position to establish scientifically the groundwork of a non-miraculous history of the development of the human race... If any person feels the necessity of conceiving the coming into existence of this matter as the work of a supernatural creative power, of the creative force of something outside of matter, we have nothing to say against it. But we must remark, that thereby not even the smallest advantage is gained for a scientific knowledge of nature. Such a conception of an immaterial force, which as the first creates matter, is an article of faith which has nothing whatever to do with human science. Where faith commences, science ends."
"In this mighty Â“war of culture,Â” affecting as it does the whole history of the World, and in which we may well deem it an honor to take part, no better ally that Anthropogeny can, it seems to me, be brought to the assistance of struggling truth. The history of evolution is the heavy artillery in the struggle for truth."
"It is, however, a most astonishing but incontestable fact, that the history of the evolution of man as yet constitutes no part of general education. Indeed, our so-called Â“educated classes" are to this day in total ignorance of the most important circumstances and the most remarkable phenomena which Anthropogeny has brought to light."
"Neither of the primitive men we have spoken of, nor of those who immediately succeeded them, can we rightly predicate any knowledge of nature."
"Ontogeny is a short and quick repetition, or recapitulation, of Phylogeny, determined by the laws of Inheritance and Adaptation."
"Our concern is rather with the unparalleled influence that Darwinism, and its application to man, have had during the last forty years on the whole province of science; and at the same time, with its irreconcilable opposition to the dogmas of the Churches."
"Our monistic view of the world belongs, therefore, to that group of philosophical systems which from other points of view have been designated also as mechanical or as pantheistic."
"Our personal life is a hundred times finer, longer, and more valuable than that of the savage, because it is a hundred times richer in interests, experiences, and pleasures."
"Phylogeny and ontogeny are, therefore, the two coordinated branches of morphology. Phylogeny is the developmental history [Entwickelungsgeschichte] of the abstract, genealogical individual; ontogeny, on the other hand, is the developmental history of the concrete, morphological individual."
"The Caucasian, or Mediterranean man (Homo Mediterraneus), has from time immemorial been placed as the head of all races of men, as the most highly developed and perfect."
"The causal character of the relation which connects embryology with stem-history is due to the action of heredity and adaptation."
"The difference between the reason of a Goethe, a Kant, a Lamarck, or a Darwin, and that of the lowest savage, a Vedda, an Akka, a native Australian, or a Patagonian, is much greater than the graduated difference between the reason of the latter and the most "rational" mammals, the anthropoid apes, or even the papiomorpha, the dog, or the elephant."
"The common origin of man and the other mammals from a single ancient stem-form can no longer be questioned; nor can the immediate blood-relationship of man and the ape."
"The gulf between this thoughtful mind of civilized man and the thoughtless animal soul of the savage is enormous -- greater than the gulf that separates the latter from the soul of the dog."
"The doctrine of derivation, or theory of descent, as a comprehensive theory of the natural origin of all organisms, assumes that all compound organisms are derived from simple ones, all many-celled animals and plants from single-celled ones, and these last from quite simple primary organismsÂ—from monads. As we see the organic species, the multiform varieties of animals and plants, vary under our eyes through adaptation, while the similarity of their internal structure is reasonably explicable only by inheritance from common parent-forms, we are forced to assume common parent-forms for at least the great main divisions of the animal and vegetable kingdoms, and for the classes, orders, and so forth."
"The purpose of this candid confession of monistic faith is twofold. First, it is my desire to give expression to that rational view of the world which is being forced upon us with such logical rigor by the modern advancements in our knowledge of nature as a unity, a view in reality held by almost all unprejudiced and thinking men of science, although but few have the courage (or the need) to declare it openly. Secondly, I would fain establish thereby a bond between religion and science, and thus contribute to the adjustment of the antithesis so needlessly maintained between these, the two highest spheres in which the mind of man can exercise itself; in monism the ethical demands of the soul are satisfied, as well as the logical necessities of the understanding."
"The real cause of personal existence is not the favor of the Almighty, but the sexual love of one's earthly parents."
"The doctrine of elimination, or the selection theory, as the doctrine especially of "choice of breed or selection," assumes that almost all, or at any rate most, organic species have originated by a process of selection; the artificial varieties under conditions of domesticationÂ—as the races of domestic animals and cultivated plantsÂ—through artificial choice of breeds; and the natural varieties of animals and plants in their wild state by natural choice of breeds: in the first case, the will of man effects the selection to suit a purpose; in the second, it is effected in a purposeless way by the "struggle for existence." In both cases the transformation of the organic forms takes place through the reciprocal action of the laws of inheritance and of adaptation; in both cases it depends on the survival or selection of the better-qualified minority."
"The progressive expansion of Christianity has killed every science, but above all natural philosophy, which necessarily had to oppose it in a hostile manner!"
"The value of the life of these lower savages is like that of the anthropoid apes, or very little higher. All recent travelers who have carefully observed them in their native lands, and studied their bodily structure and psychic life, agree in this opinion."
"They throw light first of all on the "natural history of creation," then on psychology, or "the science of the soul," and through this on the whole of philosophy. And as the general results of every branch of inquiry are summed up in philosophy, all the sciences come in turn to be touched and influenced more or less by the study of the evolution of man."
"The science of comparative anatomy. Its task is, by comparing the fully-developed bodily forms in the various groups of animals, to learn the general laws of organisation according to which the body is constructed; at the same time, it has to determine the affinities of the various groups by critical appreciation of the degrees of difference between them."
"These two branches of our science--on the one side ontogeny or embryology, and on the other phylogeny, or the science of race-evolution--are most vitally connected. The one cannot be understood without the other."
"This demand, that the doctrine of descent should be grounded on experiment, is so perverse and shows such ignorance of the very essence of our theory, that though we have never been surprised at hearing it continually repeated by ignorant laymen, from the lips of a Virchow it has positively astounded us. What can in this case be proved by experiment, and what can experiment prove?"
"Though the great differences in the mental life and the civilisation of the higher and lower races are generally known, they are, as a rule, under-valued, and so the value of life at the different levels is falsely estimated. It is civilisation, and the fuller development of the mind that makes civilisation possible, that raise mans so much above the other animals, even his nearest animal relatives, the mammals. But this is, as a rule, peculiar to the higher races, and is found only in a very imperfect form or not at all among the lower. These lower races (such as the Veddahs or Austrailan negroes) are psychologically nearer to the mammals (apes or dogs) than to civilised Europeans; we must, therefore, assign a totally different value to their lives."
"We need but mention the mighty influence which irrational dogmas still exercise on the elementary education of our youth, we need but mention that the state yet permits the existence of cloisters and of celibacy, the most immoral and baneful ordinance of the Â“only-savingÂ” church; we need but mention that the civilized state yet divides the most important parts of the civil year in accordance with church festivals; that in many countries it allows the public order to be disturbed by church processions, and so on."
"We may now give the following more precise expression to our chief law of biogeny:Â— The evolution of the foetus (or ontogenesis) is a condensed and abbreviated recapitulation of the evolution of the stem (orphylogenesis); and this recapitulation is the more complete in proportion as the original development (orpalingenesis) is preserved by a constant heredity; on the other hand, it becomes less complete in proportion as a varying adaptation to new conditions increases the disturbing factors in the development (or cenogenesis)."
"We see that man entirely resembles the higher mammals, and most of all the apes, in embryonic development as well as in anatomic structure. And if we seek to understand this ontogenetic agreement in the light of the biogenetic law, we find that it proves clearly and necessarily the descent of man from a series of other mammals, and proximately from the primates."