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Animals (History, Parts, Movement, Progression, Generation)


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The History of Animals translated by D'Arcy Wentworth Thompson

History in this context seems to denote a broad description of the lifecycle of animals, which is done first with basic anatomical features, then describing processes like sexual reproduction.

Book I 

Aristotle says that the the back of the head is empty in all animals. It isn't as if he didn't ever cut open a head, because he mentions the cerebellum. He also mentions connections with the brain from the eyes and the nose. What does he mean by empty when he already describes how the head is completely filled up? The back of the head might refer to below the cerebellum.


An entire chapter is devoted to the chameleon. Elephants are also mentioned quite a bit.


The description of systems with veins in particular may hold well, but the proof of its accuracy is not equally easy in all cases. This emphasizes the observational nature of the book, because the reason is that veins are not easily seen.


Most sentences make no mention of who is doing the observing and who is doing the recording. But one sentence says "they tell us that...", which makes me wonder if all of this is collected by a research team as guided by Aristotle as the project lead.


I don't know why some animals are thought to be spontaneously generated, specifically animals like sponges, sea anemones, certain kinds of shelled animals, and some kinds of insects that grow from grubs, and some others. My guess is that these conditions are all met: it is hard to find or observe mating, hard to observe the eggs, and the young only appear in very specific materials. The idea also seems to acknowledge that life originates somewhere. The first life forms came from inanimate material. So implicitly, Aristotle and his students realized that life is a natural part of the world and does not need conscious guidance to appear. 

Elsewhere, in the context of eggs, it is mentioned how it is possible that life can be engendered by methods besides mating and copulation. But the working assumption is that there is no other method since none is known. So since we know now that some animals reproduce asexually and other animals indirectly mate, I'm sure that this theory of spontaneous generation would be easily fixed.


There is extensive description of how the chicken embryo develops in the egg. It's understood that different parts develop in different orders. I wonder though if Aristotle developed his major theories about teleology from these observations. Life is clearly a developing process going towards some developed end, and no prior step is "complete". 


Chapter 7 doesn't seem to fit because it's about animals in general. Same as Chapter 8. Chapter 7 says all animals develop in the same way, but it isn't clear what span of time "develop" refers to. Since it talks about when birth happens, develop properly refers to how the embryo develops. So even spontaneously generated animals would develop this way, that is, gradually and in parts. Since these 2 chapters diverge so far from the book (which is exclusively about human development), the editing must be off.


Aristotle said that the life of animals can be divided into procreation and feeding. He recognized that variety of animals and types of animals depend on locality, as well as their character in terms of how they act in their environment. These are all things implicitly necessary to understand evolution, so it makes sense why biologists can get so much use out of Aristotle's thinking about life.


Much is said about animal intelligence. In particular, I like the observations about dolphins. Aristotle clearly acknowledges their capacity as social creatures, as well as elephants. There is a lot of detail about bees and of their social nature, not to mention the details about the hive. The message here is attention to detail, and looking at the world. 

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On the Parts of Animals translated by William Ogle

Book I

1 - 

The generation of animals is compared to art that people create. Sometimes it might seem to exist spontaneously without any particular reason except something like "vertebratae are formed because the spine was broken as a fetus" but the fact is that there is a necessary and complete process to reach a certain point.

The formal causes most important to consider with animals. Life is not simply an arrangement of materials.

Hypothetical necessity is something like: "if you want to chop wood with an axe, the axe needs to be hard. If you want to axe to be hard, it must be made out of bronze or iron." This is what is required to reach the final end.

2 to 4 -

This is entirely about classification, pretty much how things can fit under a genus and differentia system. You can't simply break everything down as a dichotomy all the way down, or else a species may sometimes be a member of multiple classes.

5 - Aristotle clearly says that a body part serves some end. The body is made for the soul (the process of life), and body parts are made for the soul's subordinate functions.

Book II

7 - Aristotle talks about how the brain has a cold nature. By that he means, in this case, not that the brain is cold to touch, but that its nature has to do with processes involving coldness.

He is well aware that the brain has no sense of touch, that its material is discontinuous anatomically, and it is discontinuous with sensation. The operations of the soul in part are of a fiery nature, in terms of how heat best produces the energy necessary for the soul's activities - particularly nutrition and locomotion. By being of a cold nature, the brain would therefore serve a different function than preservation of the whole body. So Aristotle proposes that the brain cools the blood to prevent it from reaching extremes. It is worth noting that he doesn't say anything about the brain and reason.

8 - All the other parts exist for the sake of the flesh. The reason is that all animals have sense, and touch is present in all animals, unlike the other senses. Although Aristotle seems to distinguish flesh and skin, I can't tell the difference he implies.

9 - Bone is a homogenous material, for the most part, so would normally be expected to form something continuous. But because animals need to move for locomotion, bones are divided.

10 - Aristotle says that parts are more complicated for animals who live life to a higher degree. He also says that man is closer to the divine than other animals, in the sense that man engages in reasoning more fully than any other animal. For these reasons, he wants to examine man primarily, or at least begin there for the next chapters.

I can see how a Christian like Aquinas would take Aristotle literally when he says that we should speak of man first because of "his upper part being turned towards that which is upper in the universe". Metaphorical speech makes sense in this context, because it is used as a transition to a different subject.

Aristotle says that the brain cannot be the cause of sensation, because the brain itself provides no way to feel. This is certainly true, or at least this is a good reason to say that the brain isn't the source of sensation. Importantly, he says that properly cooled and pure blood makes senses more precise, so that's why the sensory organs are mostly in the head - the brain does the cooling. Although his explanation of the brain is still incorrect, Aristotle seems to implicitly recognize that the brain does something really important in connection with sensation and perception.

12 - Aristotle says that the seal has a stunted development, so I take this to mean that he doesn't really have a conception of adaptations developing over time. Although he has the starting ideas of evolution, Aristotle doesn't consider asking if the adaptive way an individual animal is generated (or born) can also generate new species.

16 - With some structural modifications, the human mouth can be shaped into a beak. Aristotle recognizes implicitly that structurally, animals are formed from something common. Or maybe explicitly, because he also recognizes that of animals who have hearts, the heart will develop first. His example might even be based on his study of developing chickens.

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1 - Teeth are treated in terms of their adaptive function. Teeth can be weapons, or simply the way to break down food, but in either case they exist to fulfill a function of eating. It is mentioned that males have stronger teeth because they are stronger than females, and some people interpret this as applying to all species, but the context where this is said seems to be about animals who use their teeth as weapons or defense.

2 - The material that a part of is made out of is a limited resource in the animal. I'm not sure where Aristotle gets this idea, other than he seems to treat balance within an organism as a key principle, as he does when he says that the brain needs to cool the blood to maintain a balanced temperature. Here, he says less material used for teeth means more material for horns and tusks, since all of these things are forms of teeth.

4 - He says that the heart is the only part that can't tolerate any serious damage or affects. True enough, for the heart specifically. But what about the brain? Although the brain can receive substantial damage and the person doesn't die, even though sometimes they will die depending on where the damage is. I wonder if this conclusion is because Aristotle didn't know the actual function of the brain, or because he observed people who received substantial brain injuries.

7 - All the organs are double. I think this is not intended as a universal statement, as he always recognizes there are exceptions in the parts of animals. Some specific organs are singular, but they seem to be paired with a relatively similar organ, such as the spleen and the liver.

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4 - Why do sea-urchins have 5 ova? Aristotle explains by reference to how they are shaped as spheres. Being spherical, they are shaped symmetrically. Normally, a ring arrangement would be good enough for the ova because of this. But this can't be because their genus (tribe) has no symmetrical arrangement of ova, and the ova are positioned on one side of the body. So an odd number of ova it is necessary; even numbers would mean positioning on opposite sides in pairs. Moreover, 3 would be too few to be useful, more than 5 too many. It is basically a form follows function argument.

10 - The adaptability of man is what puts him at an advantage compared to other animals. He can change at will; the hand is talon, hoof, horn, and spear. The hand is well adapted to this diversity of action. This is also a reason that intelligence is not a consequence of the hands, but that the hands are a consequence of intelligence. In other words, parts serve functions, functions do not serve parts.

13 - Aristotle recognizes how strange ostriches are. He still counts them as birds, he isn't absolutely rigid about categories. But he sets them aside for later consideration.

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Progression of Animals translated by A. S. L. Farquharson

How and why are limbs constructed to accomplish locomotion?

2 - Three different dimensions are assumed essential for this inquiry: top and bottom, front and back, left and right

5 - I get the sense that the word superior is not translated very well throughout this book, because the translator might interpret what is intended as position or metaphor for a position instead as some kind of metaphysical superiority. Aristotle seems to be actually saying that animals have their most important parts positioned relative to the way they physically stand in the universe, ie in the superior-inferior line. And this is where movement starts, since nature creates what is best for a given animal, so of course animals start moving through those most important parts and would begin movement with the most important parts. This is more consistent with what Aristotle said in this book, instead of a vaguely theological answer about "position in the universe" for why starting points are placed as they are.

8 - This is a decent explanation of why snakes are not built like centipedes and why no limbs at all are better than any. For one, no blooded animal has more than 4 legs. Secondly, by being so long, 2 or 4 legs would result in slow and inefficient movement. One or 3 legs would result in an inability to shift weight properly. This is a thoroughly functional answer.

17 - Peculiarities about parts of the body, like a flat fish having a twisted head, leads to a peculiarity of the entire shape of the animal compared to what you would expect for animals like them.

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Movement of Animals translated by A. S. L. Farquharson

What causes movement in change of place? That's the main question here. As usual, I don't like this translator.

1 - Each animal as a whole must have a point of rest within itself from which to originate movement.

2 - The point of rest is still useless unless there is an external point that is at rest. Otherwise it is like pushing a boat with a stick from inside itself.

3 - Atlas fable used as thought experiment. He seems to imply that the fabulist's view entails that the earth would not be in a position that's part of the universe. If Atlas initiates movement of the heavens, he has to push against the earth. If the earth is at rest, then Atlas is pushing against the earth with the same amount of force that the earth resists with. Superior force by Atlas is required in order to for him to move the heavens. All of this would imply that the earth would be pushed away and out of the universe. Or, the earth would have to give as much force as the entire heavens and Atlas, which is also impossible, because the earth cannot have infinite force.

4 - Animals must in addition have an immovable point within itself, in terms of its own parts.

6 - The object of desire or intellect initiates movement in animals. These things only initiate movement to the extent that those objects are for the sake of something else. After this it sounds like Aristotle says that the eternally moved by the prime mover, is moved like an animal, almost as if the universe is conscious, but I think he means that the likeness is that of the previous chapters, and the difference from animals is that animals are not eternal. So the prime mover moves things by virtue of its perfection and requires no faculty or desires, but animals use desire to move things or themselves.

7 - When a man actualizes himself in relation to an object by perception, imagination, or conception, he does what he desires at once.

8 and 9 - Aristotle suggests a central point or primary point for the soul to originate movement, but he focuses on a physical point to move from for the soul to be a source of movement. He seems far from conceiving of a source or originating point that isn't solid, like electricity.

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Generation of Animals translated by Arthur Platt

How animals must come to be.

Book I

2 - The essence of male and female is in terms of their function for generating offspring. The essence is not behavioral, anatomical, or anything normative. When this essential feature is altered, many other changes in the animal follow, so this is a reason that sex is a first principle.

17 and 18 -

Far into these sections Aristotle defined semen as: that which has in its the principles from both united parents, as the first mixture which arises from the union of male and female

Aristotle discusses two competing theories of what semen comes from, that is, what enables it to shape the nature of offspring.

Argument that semen comes from the whole body:
1) the intense pleasure of sex
2) mutilations allegedly can be inherited
3) children resemble parents
4) if the whole arises from one thing, so too does each part, therefore semen gets the "first thing" for each part in the child from each part in the parent.

3: Offspring sometimes look more like several generations prior.

Does semen instead come from either homogenous parts, or heterogeneous parts? Homogenous is more fitting because the heterogeneous comes from the homogenous. If semen comes from both, then it comes from the composition of the homogenous. But this would mean that semen comes from some other underlying thing (like the elements). By analogy: if something comes from a name, it comes from the syllables. If something comes from the syllables, it comes from the letters and composition. Homogenous parts are made of something, a composition of things, so the underlying thing would be the actual place where semen comes from. Of course, today we know that there is something even underlying what homogenous parts are made of, and that is DNA.

If the parts of the offspring are in the semen, how could they live? And if they were connected, they would already be an animal - how semen contributes to this is the question in the first place.

Female parts don't resemble male parts, so semen couldn't come from every part.

If a part not identical to blood can be produced by blood, then something not identical to blood can produce blood. In the same manner, semen does not need something from every part, but might need only something from one part.

Men and women both can change from producing male offspring to producing female offspring. So it seems that the cause is a mutual proportion that comes from men and women. If this is true, then semen doesn't come from any particular part.

How could many animals be generated from one act of mating if semen came from every part? How could the semen be distributed across all of the potential offspring?

1: the pleasure is caused by the friction involved in sex
2: the offspring are not consistently mutilated

I detailed this because it's a thorough scientific argument about theory. There is absolutely nothing about the supernatural in any sense.

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20 - Catamenia are semen in the sense that they need to be worked on in order to generate. Although this fact is wrong, it still recognizes that females aren't simply receptacles.

22 - Semen sets up the movement of the material, and by doing so imparts shape and form. This motion varies along with the nature of what is made. In either case, Aristotle mentions no formal cause of generation, just efficient and material.

23 - There is a wonderful passage about why existence is better than nonexistence for a living thing.

Book II

1 - The eternal causes the better in things that are capable of being better or worse. This makes sense insofar as reality is eternal and that the eternal nature makes it so reality is determinate. Since living is better than not living, there should be something in a sense "more eternal" about life. Individual things cannot be eternal, but across time a species is eternal in terms of that species is continuing. This is how we explain the nature of generation, in terms of final cause. (Seems close to evolution as a final cause.)

That which makes the parts is first suggested to be a motion that occurs mechanically, by nature of the semen itself it seems. And if this is so, for animal generation, whatever makes the parts does not exist as something definite. The question is left here. But all of this is true of genes.

If one organ forms the other, such as the heart forming the liver, then the form of the created thing would exist in the original organ. The form of the liver would be in the heart.

3 - Aristotle says that reason (the rational soul) could enter the body from the outside, unlike the sensitive and nutritive soul. He says it's because no bodily activity has any connection to it, which is literally true in the sense that reasoning is about abstract things. But I'm not sure what entering from the outside would be, or if this is necessarily mystical as it sounds. My only charitable interpretation is that he means the rational soul develops through learning after generation, that it doesn't exist during generation. 

6 - Hearing, and smell, are through passages in the body. Touch and taste by the body itself. Only the eyes are a particular entity for a particular sense. This is why they might form so late. Aristotle also notes that having the largest brain is caused by having the purest heart, and this fact indicates intellect.

7 - Aristotle recognizes that any sufficiently similar animals produce the same animal when they copulate. But it sounds like same animal really just means same type, like wolf, so he doesn't actually think that animals remain all the same throughout time and history. 

8 - There is an abstract proof of why mules are sterile. The proof is sensible enough, in that it is logically consistent from the premises, and the conclusion itself is what is seen in reality. But then Aristotle rejects that proof because it is empty and are not based on special principles, presumably of the science of generation. Aristotle is rejecting pure deduction. His explanation is instead generally that the animals that generate mules tend towards sterility as it is. Crossbreeding is difficult as it is, so it might make sense that the resulting children are even more sterile than parents.

Edited by Eiuol
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Book III

2 - Intelligence is in the greatest proportion in the animals that show love and familiarity to their young. This is mentioned in relation to survival benefit to the young.

4 - Aristotle notices that greater gestation time and greater size of the young contributes to decreasing how many young are produced.

10 - A great deal is said about how bees generate, especially to argue against existing theories about bees. It's all sensible enough, based on observation. Yet Aristotle acknowledges directly that this is what appears to be the truth, and specifically based off of premises, but that all the facts are not sufficiently grasped yet. He says that credit must be given first to observations rather than theories, and theories only if they agree with observed facts.

Book IV 

1 - Aristotle mentions other theories about how male and female is differentiated during development, but basically in the end dismisses any thorough refutation because they are not based on facts as they are now understood.

Nature assigns an organ to the corresponding faculty.

2 - This chapter interestingly allows for an easier interpretation of virtue as a mean. By analogy, too much fire burns meat, too little fire doesn't cook it. In either case, the process is a failure. The focus is actually on a successful process caused by the proper proportion of characteristics.

Aristotle speaks of an embryo becoming male when it prevails in its movement, which makes me think of Nietzsche because there is a certain biological willing that occurs. Although it can also be thought of as certain requirements being met compared to a default. All embryos actually start out as female, so in a way Aristotle is right, because becoming male must be actively created during development. But he also mentions the individual prevailing or the male principle prevailing.

4 - Monstrosities are contrary to nature, but only contrary in the sense of contrary to how things usually are but can still happen in other ways.

6 - Nutriment in development goes towards the size of the young, or in the other direction towards the number of young.

Book V

This book makes much more sense either in Parts, or History. Nothing is about generation. It actually makes most sense with Meteorology book IV. This book deals with hot and cold affecting organic things. Book V of Generation deals with hot and cold producing incidental traits in animals, such as hair color, eye color, and characteristics of skin. On the other hand, it does describe the generation of incidental characteristics.

These characteristics are not because of any final cause about the animal. There can be numerous causes concretely speaking, these characteristics don't have to be because of an animal's definition.

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