J. B. Lamarck 

Zoological Philosophy 
Volume I

[This translation, which has been prepared by Ian Johnston of Malaspina University College, Nanaimo, BC, Canada, is in the public domain, and may be used by anyone, in whole or in part, without permission and without charge, provided the source is acknowledged, released September 1999]


Preliminary Discourse

Observe nature. Study her productions. Carry out research into the general and particular interconnections which she has impressed on their characteristics. Finally try to grasp the order which she has brought into being everywhere, as well as her progress, her laws, and the infinitely varied ways which she uses to give rise to this order--that is, in my view, to put oneself in a position to acquire the only reliable knowledge at our disposal (the only one, moreover, which can be truly useful to us) and at the same time to gain the sweetest pleasures, those most appropriate to assuage the inevitable pains of life.

In fact, what is more interesting in the observation of nature than the study of the animals, than thinking about the connections between their structure and that of human beings, about the power which their habits, ways of life, climates, and environments have to modify their organs, faculties, their characteristics, than an analysis of the different structural systems which we see among them and according to which we determine the relationships, some important, others less so, which fix the rank of each one in the natural order. Finally, what is more interesting than the general arrangement which we establish for these animals, taking into account the greater or lesser complexity in their structures, an arrangement which can lead to an understanding of the very order which nature has followed in bringing each species into existence?

Certainly one cannot deny that that all these questions and several others as well which the study of animals necessarily leads to are of great interest to anyone who loves nature and seeks the truth in everything.

What is odd is that the most important phenomena to consider have only been available for our reflections since the time when people concerned themselves mainly with the study of the least perfect animals and when research into the different complexities in the structures of these animals became the main basis of their study.

It is no less odd to be forced to acknowledge that it was almost always from the sustained examination of the smallest objects which nature presents to us and from the most apparently minute considerations that we have obtained the most important knowledge for discovering nature's laws and methods and for determining her progress. This truth, already confirmed by many remarkable facts, will receive new evidence in the matters revealed in this work, and we must be convinced more than ever that, so far as the study of nature is concerned, no object whatsoever is unworthy of attention.

The purpose of the study of animals is not exclusively to understand their different races and to determine all the distinctions among them by establishing their special characteristics. It is also to reach an understanding of the origin of the faculties which they enjoy and of the causes which brought them into existence and now maintain their lives and, finally, the causes of that remarkable progression which they display in their form and structure and in the number as well as in the development of their faculties.

At their source, the physical and the moral are, without doubt, only one and the same thing. And by studying the organic structure of the different orders of known animals, we can provide the most impressive evidence for this truth. Now, as the products of this source are effects and since these effects, at first distinguished from each other with difficulty, have subsequently separated into clearly distinct orders, these two groups of effects, the physical and the moral, considered in their most important distinction, have appeared to us and still appear to plenty of people to have nothing in common between them.

However, the influence of the physical upon the moral has already been recognized (1). But it seems to me that we have not yet given sufficient attention to the influence of the moral on the physical itself.  Now, these two orders of things, which have a common source, react upon each other, above all when they appear the most separate, and we have nowadays the means to prove that they change themselves in one way or another in their variations.

It strikes me that we have gone wrong in our efforts to demonstrate the common origin of the two orders of effects, which, when most distinct from each other, make up what we call the physical and the moral. We have chosen a road opposite to that which must be followed.

In fact, people started to study these two sorts of things, apparently so distinct, in man himself, where the organic structure, having reached the limit of its design and perfectibility, displays the greatest complexities in the causes of the phenomena of life, of feeling, and finally of the faculties he enjoys. In man, thus, it is most difficult to grasp the source of so many phenomena.

After having thoroughly studied the organic structures of man, as people have done, rather than fussing about with research into the very causes of life in this structure, the causes of physical and moral sensation, in a word, of the lofty faculties he possess, we then had to try hard to understand the structure of other animals, to consider the differences which exist among them in this respect, as well as the connections which occur between the faculties which are appropriate to them and the organic structure which they have been given.

If these different things had been compared with each other and with what was known concerning man, and if people had taken into account, from the organic structure of the simplest animals right up to that of man, the most complex and the most perfect, the progression manifest in the complexity of the organic structure as well as the successive acquisition of different specialized organs, and consequently of so many new faculties which the new organs bring, then people could have seen how needs, at first reduced to nothing, but then gradually increasing in number, have led to a tendency for actions appropriate to satisfy those needs. They could have seen how, once these actions became habitual and energetic, they brought about the development of organs which carry them out; and how the force which stimulates organic movements can, in the most imperfect animals, be located outside of them and nevertheless animate them, how later this force was moved and fixed in the animal itself, and finally, how this force has there become the source of sensibility and at last of intelligent action.

I will add that if people had followed this method, then they could not have considered feeling as the universal and immediate cause of organic movements and could not have said that life is a series of movements carried out by virtue of sensations received by the different organs or, alternatively, that all the vital movements are the product of impressions received by the sensing parts. Rapp. Du phys. Et du moral de l'Homme, p. 38 to 39, and 85.

This cause would appear to be, up to a certain point, based upon a consideration of the most perfect animals; but it was also relevant to all the bodies which enjoyed life: they all possessed the faculty of feeling. Now, people did not know how to show us that plant life is in the same condition; people did not know even how to prove that this was the case with all the known animals.

I do not acknowledge at all the assumption of such an allegedly universal cause for the real march of nature. In creating life, she did not start suddenly by establishing such a high faculty as that of feeling. She did not have the means to bring such a faculty into existence in the imperfect creatures of the first classes in the animal kingdom.

With respect to the bodies which enjoy life, nature made everything gradually and successively; there is no longer any possible doubt about that.

In fact, among the different things which I propose to explain in this work, I will try to reveal, by referring throughout to known facts, that in making animals' organic structures increasingly complex, nature has progressively created different specialized organs as well as the faculties which the animals enjoy.

For a long time it has been thought that there existed a sort of ladder or graduated chain among the bodies endowed with life. Bonnet developed this view, but he did not prove it by facts derived from organic structure itself; that, however, was necessary, especially in relation to animals. He could not do it, because at the time he lived people did not yet have the means.

As one studies animals of all the classes, there are plenty of things to see other than the growing complexity in animal organic structure. The production of causal circumstances leading to new needs, those needs giving rise to actions, those repeated actions creating the habits and inclinations, the results of increased or diminished use of some organ or other, the means which nature uses to preserve and improve everything acquired in the structure, and so on and so on--these are things of the highest importance for rational philosophy

But this study of animals, especially of the less perfect ones, was for a long time neglected; we were so far from suspecting the great interest which it could provide. And what has been started in this respect is still so recent, that in pursuing it, we have reason to expect many new insights.

When people started truly to cultivate natural history and each kingdom attracted the attention of naturalists, those who directed their research into the animal kingdom studied mainly the vertebrates, i.e., mammals, birds, reptiles, and finally fish. In these classes of animals, since the species are generally larger, have more developed parts and faculties, and are more easily characterized, they appeared to offer more interesting material to study than those which belong to the division of invertebrate animals.

In fact, the extremely small size of most of the invertebrates, their limited faculties, and the fact that their organs have a much more distant relationship to human ones than the ones we observe among the more perfect animals--these made them, in some ways, commonly despised and, right up to our time, gave them only a very luke-warm interest for the majority of naturalists.

However, we are beginning to retreat from this prejudice harmful to the advancement of our knowledge, for in the past few years, when these remarkable animals have been examined attentively, we have been forced to recognize that the study of them must be considered one of the most interesting for the naturalist and the philosopher, because it sheds light onto a number of problems relevant to natural history and animal physics, insight which it would be difficult to obtain in any other way.

When I was given the task in the Museum of Natural History of making displays of animals which I call invertebrates (because of their lack of a vertebral column), my research on these numerous animals, the observations and facts which I collected concerning them, and finally the insights which I borrowed from comparative anatomy with respect to them soon gave me the keenest idea of the interest which a study of them inspires.

In fact, the study of invertebrates must be of special interest to the naturalist. First, the species of these animals are much more numerous in nature than the vertebrate species. Second, since they are more numerous, they are necessarily more varied. Third, the variations in their organic structure are much greater, more clear cut, and more peculiar. Finally, the order which nature uses to form in succession the different animal organs is much better expressed in the mutations which these organs undergo in the invertebrates and makes the study of them much more appropriate for getting us to see the very origin of organic structure, as well as the reason for its complexity and development. All the issues revealed by the more perfect animals, like the vertebrates, could not achieve this.

Once I was struck with these truths, I felt that, in order to make them comprehensible to my students, rather than burying myself right from the start in details about particular things, I must, above all, present to them the general truths relevant to all the animals, to show them the entire collection, along with the essential considerations pertinent to such a collection. I proposed after that to grasp the principal groups which seemed to divide up this collection in order to establish comparisons among them and to make the students better understand each one separately.

In fact, the true way to arrive at a full understanding of something, even in its smallest details, is to start by envisaging it in its entirety, by an initial examination, whether of its mass, its extent, or the collection of parts which make it up, by researching what its nature and origin are, what are its connections to other known things, in a word, by considering it from all the points of view which can illuminate for us all the general truths which concern that thing. Later one divides the object under investigation into its principal parts in order to study them and consider them separately in connection with all those interrelationships which can tell us things about them; and continuing in this way to divide and sub-divide these parts examined in succession, we go right down to the smallest, whose particular details we study, not overlooking the least details. When all this research is finished, one tries to deduce from it the consequences, and little by little the philosophy of science establishes, corrects, and perfects itself.

Only by this path can human intelligence acquire the most far reaching, most reliable, and most fully coordinated knowledge in any science whatsoever. And it is solely by this method of analysis that all sciences make true progress and that the things that they deal with are not confused and can be perfectly understood.

Unfortunately, we are not sufficiently in the habit of following this method in studying natural history. The acknowledged necessity for good observation of particular objects has given birth to the habit of limiting oneself to the consideration of these things and of their smallest details, in such a way that for the majority of naturalists that has become the main subject of study. This, however, would really slow down the natural sciences if we persist in not seeing anything in the objects observed except their shape, dimensions, external parts, even the smallest, their colour, and so on and if those who undertake such a study refuse to rise up to some loftier considerations, for example, to seek out the nature of these things which they are busy with, the causes of the modifications or the variations to which these things are all subject, the interrelationships of these same things amongst themselves and with all the others which we know about, and so on.

Because we have not followed sufficiently the method which I have just mentioned, we notice such a divergence in what is taught in these matters, whether in the works of natural history or elsewhere, and those who specialize in the study of species do not grasp, except with great difficulty, the general interconnections among things, not perceiving anything of the true plan of nature and recognizing hardly any of her laws.

Convinced, on the one hand, that we must not follow a method which restricts and limits our ideas in such a way, and on the other hand finding myself needing to publish a new edition of my System of Invertebrate Animals, because the rapid progress in comparative anatomy, the new discoveries by zoologists, and my own observations gave me the means to improve this work, I thought I should collect in a single work under the title of Zoological Philosophy the following: (1) the general principals relevant to the study of the animal kingdom, (2) the essential observed facts which one needs to take into account in this study, (3) the considerations which govern the non-arbitrary distribution of animals and their most suitable classification, and finally (4) the most important consequences which one infers naturally from the observations of collected facts and which are the basis of the true philosophy of science.

The Zoological Philosophy in question is nothing other than a new edition, put on a fresh basis, corrected, and much enlarged of my work entitled Research into Living Organisms. It is divided into three main parts, and each of these parts is divided into different chapters.

Thus, in the first part, which should present the essential observed facts and the general principles of the natural sciences, to begin with I am going to consider what I call the artistic parts of the sciences under review, the importance of taking into account the interconnections, and the idea that one must form of what is called a species among living bodies. Then, after having developed the general truths relevant to animals, I will lay out, on the one hand, proofs of the degradation in the organic structure governing the animal scale from one extremity to the other, the most perfect animals standing at the front part of this scale and, on the other hand, I will show the influence of circumstances and habits on animal organs, how these are the root causes which favour or prevent organic development. I will end this section by considering the natural order of animals and by revealing their distribution and their most suitable classification.

In the second part, I will set forth my ideas on the order and the condition of things which create the essence of animal life, and I will indicate the essential conditions for the existence of this admirable phenomenon of nature. Then I will attempt to determine the causal stimulus of organic movements, those of orgasm and of irritability, the properties of the cellular tissue, the unique circumstance in which spontaneous generation can taken place, the manifest consequences of living acts, and so on.

Finally, the third part will present my opinion on the physical causes of feeling, on the power of action, and the acts of intelligence in certain animals.

I will deal there with the following: (1) the origin and the formation of the nervous system; (2) the nervous fluid which can be known only indirectly, but whose existence is attested to by phenomena which it alone can produce; (3) physical sensibility and the mechanism of sensations; (4) the force producing animal movements and actions; (5) the source of will or the faculty of willing; (6) ideas and their different orders; and finally (7) some particular acts of understanding, like attention, thoughts, imagination, memory, and so on.

The topics revealed in the second and the third part include, without doubt, some subjects very difficult to examine and even some apparently insoluble questions. But they hold so much interest that some attempts to deal with them could be advantageous, whether pointing out some unperceived truths or opening the way which possible leading to them.


Notes to the Preliminary Discourse

(1) See the interesting work of M. Cabanis, entitled Rapport du physique et du moral de l'Homme. [Back to Text]