THE ATOMISTS
LEUCIPPAS (fl. 440-435 B.C.) &
DEMOCRITUS (460- )
Leucippas may have come from Miletus; however, little is known about him. He is said to have written two books, On Mind and The Great World System. He is accepted as being the first to devise the theory of atoms and the void (atomism). Democritus came from Abdera, in Thrace in Northern Greece, and did indeed associate with Leucippas. He traveled a great deal. He wrote many works (at least seventy) on varied subjects, including The Little World System, in homage to his teacher.
What Is and What Is Not
1. 'Leucippus and his associate Democritus declare the full and the empty [void] to be the elements, calling the former "what is" and the other "what is not". Of these the one, "what is", is full and solid, the other, "what is not", is empty [void] and rare. (This is why they say that what is is no more than what is not, because the void is no less than body is.) These are the material causes of existing things....' (Aristotle, Metaphysics, 1.4)
The Need for a Void
1. 'People mean by a void an interval in which there is no perceptible body. Since they believe that everything that is is body, they say that void is that in which there is nothing at all. ... So it is necessary to prove ... that there is no interval different from bodies ... which breaks up the whole body so that it is not continuous, as Democritus and Leucippus say, and many other natural philosophers, or anything outside the whole body, which is continuous. They say that there would be no change in place (i.e., motion and growth), since motion would not seem to exist if there were no void, since what is full cannot admit anything. ... Some things are seen to contract and be compressed; for example, they say that the jars hold the wine along with the wineskins, since the compressed body contracts into the voids that are in it. Further all believe that growth takes place through void, since the nourishment is a body and two bodies cannot be together. They also use as evidence what happens with ash, which receives as much water as the empty vessel.' (Aristotle, Physics 4.6)
Atoms/Thing and the Void/Nothing
1. 'Democritus believes that the nature of the eternal things is small beings unlimited in multitude. As a place for these he hypothesizes something else, unlimited in size, and he calls the place by the names "void", "nothing" and "unlimited" [of "infinite"] and he calls each of the substances "thing" and "compact" and "what is". He holds that the substances are so small that they escape our senses." (Aristotle, On Democritus, quoted by Simplicius, Commentary on Aristotle's On the Heavens 295.1)
2. 'Leucippus... posited the atoms as unlimited and ever moving elements, and an unlimited multitude of shapes among them on the grounds that they are no more like this than like that, since he observed that coming to be and change are unceasing in things that are. Further, he posited that what is is no more than what is not, and both are equally causes of what comes to be. For supposing the substance of atoms to be compact and full, he said it is "being" and that it moves in the void, which he called "not-being" and which he declares is not less than what is. His associate, Democritus of Abdera, likewise posited the full and the void as principles, of which he calls the former "being" and and the latter "not-being". (Simplicus, Commentary on Aristotle's Physics 28.4)
3. 'These men [Leucippus, Democritus and Epicurus] said that the principles are unlimited in multitude, and they believed them to be atoms and indivisible and incapable of being acted upon because they are compact and have no share of the void. (For they claimed that division occurs where there is a void in bodies.)' (Simplicius, Commentary on Aristotle's On the Heavens, 242.18)
4. 'There is no more reason for the thing to be than the nothing.'
(Plutarch, Against Colotes 1108f)
No Division to Infinity
1. 'Those who abandoned division to infinity on the grounds that we cannot divide to infinity and as a result cannot guarantee that the division cannot end, declared that bodies are composed of indivisible things and are divided into indivisibles. Except that Leucippus and Democritus hold that the cause of the primary bodies' indivisibility is not only their inability to be affected but also their minute size and lack of parts.' (Simplicius, Commentary on Aristotle's On the Heavens, 242.18)
2. 'For there is a difficulty in supposing that there is some body, a magnitude, that is everywhere divisible and this this [the complete division] is possible. For what will there be that escapes the division? ... Now since such a body is everywhere divisible, let it be divided. What, then, will be left? A magnitude? But this cannot be. For there will be something that has not been divided, whereas we supposed that it was everywhere divisible. But if there will be no body or magnitude left and yet the division will take place, either <the original body> will consist of points and its components will be without magnitude, or it will be nothing at all, so that it could come to be out of nothing and be composed of nothing, and the whole thing would then be nothing but an appearance. Likewise, if it is composed of points, it will not be a quantity. For when they were in contact it was a single magnitude and they coincided, they made the whole thing none the larger. For when it is divided into two or more, the whole is no smaller or larger than before. And so, even if all the points are put together they will not make any magnitude. ... These problems result from supposing that any body whatever of any size is everywhere divisible. ... And so, since magnitudes cannot be composed of contacts or points, it is necessary for there to be indivisible bodies and magnitudes.' (Aristotle, On Generation and Corruption 1.2) e
Atoms
1. 'Democritus <held this view> because there is by nature no perceptible substrate, whereas the atoms, which combine to form all things, have a nature deprived of every perceptible quality.' (Sextus Empiricus, Against the Mathematicians 8.6)
2. 'They declare that their nature is one, as if each were a separate piece of gold.' (Aristotle, On the Heavens 1.7)
3. 'Leucippus and Democritus said that their primary bodies, the atoms, are always moving in the unlimited void by compulsion.' (Simplicius, Commentary on Aristotle's On the Heavens, 242.18)
4. 'Democritus, saying that the atoms are naturally motionless, declares that they move "by a blow"'. (Simplicius, Commentary on Aristotle's On the Heavens, 242.18)
5. 'Democritus says that the primary bodies (these are the compact things) do not possess weight but move by knocking against one another in the unlimited, and there can be an atom the size of the cosmos.' (Aetius 1.12.6)
Atoms compose compounds
1. 'These atoms, which are separate from one another in the unlimited void and differ in shape and size and position, and arrangement, move in the void, and when they overtake one another they collide, and some rebound in whatever direction they may happen to, but others become entangled in virtue of the relation of their shapes, sizes, positions, and arrangements, and stay together, and this is how compounds are produced.'
(Simplicius, Commentary on Aristotle's On the Heavens, 242.18)
2. 'They have all kinds of forms and shapes and differences in size. Out of these as elements he generates and combines visible and perceptible bodies. <These substances> contend with one another and move in the void on account of dissimilarity and the other differences I have mentioned, and as they move they strike against one another and become entangled in a way that makes them be in contact and close to one another, but does not make any thing out of them that is truly one, for it is quite foolish <to think> that two or more things could ever come to be one. The grounds he gives for why the substances stay together up to a point is that the bodies fit together and hold each other fast. For some of them are rough, some are hooked, other concave and other convex, while yet others have innumerable other differences. So he thinks that they cling to each other and stay together until some stronger necessity comes along from the environment and shakes them and scatters them apart. He describes the generation and its contrary, separation, not only for animals but also for plants, cosmoi, and altogether for all perceptible bodies.' (Aristotle, on Democritus, quoted by Simplicius, Commentary on Aristotle's On the Heavens, 295.1)
3. 'For positing the atoms as matter for the things that are they generate the rest by means of their differences. These are three: rhythm, turning, and touching, i.e., shape, position, and arrangement. For like is by nature moved by like, and things of the same kind move towards one another, and each of the shapes produces different composition when arranged in a different compound. Thus, since the principles are unlimited, they reasonably promised to account for all attributes and substances -- how and through what cause anything comes to be. This is why they say that only those who make the elements unlimited account for everything reasonably. They say that the multitude of the shapes among the atoms is unlimited on the grounds that they are no more like this than like that. For they themselves assign this as a cause of the unlimitedness.' (Simplicius, Commentary on Aristotle's Physics, 28.4)
4. 'When Democritus said that the atoms are in contact with each other, he did not mean contact strictly speaking... but the condition in which the atoms are near one another and not far apart is what he called contact. For no matter what, they are separated by the void.' (Philoponous, Commentary on Aristotle's On Generation and Corruption 158.27)
5. 'Democritus specified two <basic properties of atoms>: size and shape; and Epicurus added weight as a third.' (Aetius 1.3.18)
Humans are atoms
1. 'What does Democritus say? That substances unlimited in multitude, atomic and not different in kind, and moreover incapable of acting or being acted upon, are in motion, scattered in the void. When they approach one another or collide or become entangled, the compounds appear as water or fire or as a plant or a human, but all things are atoms, which he calls forms; there is nothing else. For from what is not there is no coming to be, and nothing could come to be from things that are because on account of their hardness the atoms are not acted upon and do not change.' (Plutarch, Against Colotes 8)
2. 'He makes sweet that which is round and good-sized; astringent that which is large, rough, polygonal, and not rounded; sharp tasting, as its name indicates, that which is sharp in body; and angular, bent and not rounded; pungent that which is round and small and angular and bent; salty that which is angular and good-sized and crooked and equal sided; bitter that which is round and smooth, crooked and small sized; oily that which is fine and round and small.' (Theophrastus, Causes of Plants 6.1.6)
3. 'By convention [or, custom], sweet; by convention, bitter; by convention, hot; by convention, cold; by convention, color; but in reality, atoms and the void.' (Sextus Empiricus, Against the Mathematicians 7.136)