Democritus and his teacher Leucippus were the first philosophers to propose that all things were made up of the joining-together of imperceptible atoms.
Democritus was born in the city of Abdera in Thrace sometime around 460 BCE. Later accounts say he studied with the philosopher Leucippus. Leucippus is said to have authored two books: On Mind and The Great World System, neither of which has survived. Democritus was much more prolific and is said to have authored up to seventy works.
Between them, Leucippus and Democritus introduced a new idea into the Greek philosophical world: the idea that the things of the universe were constructed out of innumerable, infinitesimally small building blocks that they called atoms.
A perpetual stranger
Democritus's teacher was so obscure that even in the ancient world there was debate about his historicity: the philosopher Epicurus even argued (not entirely plausibly) that Leucippus never existed. But with Democritus, we are on more solid ground, even if our knowledge of his life remains hazy. Traditional accounts say that he was the son of a wealthy family and that he blew a large part of his fortune on travels throughout the ancient world. It is said that he was a footloose thinker — spending five years in Egypt, and travelling to Mesopotamia and even as far as India. And in each of these places, he studied with local scholars and philosophers. Democritus apparently also spent some time in Athens (“I came to Athens,” he said, “and no one knew me”), and he had at least a fleeting acquaintance with Socrates.
The philosopher of everything
Democritus was not only a prolific author; he also wrote on a bewildering variety of topics: from travel accounts to books on medicine, to works on the art of painting, to accounts of Babylonian systems of thought, to works about ethics and philosophy, to books about the shadowy underworld of Hades. Unfortunately, of all these works, only a few fragments remain.
Other than his omnivorous thirst for knowledge and understanding, the other thing that early accounts say about Democritus is that he was famed for his cheerfulness: he was known as the “laughing philosopher” (in contrast with Heraclitus, who was known as the “weeping philosopher”). And this cheerfulness seems to have served him well. Democritus is said to have died at an advanced age, somewhere between ninety and one hundred years old.
Atoms and void
Democritus and Leucippus are best known for proposing that the bewildering diversity of things in the universe is underpinned by a much simpler reality: the play of atoms in empty space. Democritus proposes an infinite void filled with atoms of various shapes and sizes, so small that they escape our senses. The Greek word atom means “that which cannot be cut.” For Democritus, an atom is the smallest possible unit upon which things can be built. Atoms are eternal and indestructible, and everything that exists emerges out of a restless soup of atoms in motion through the void.
These atoms cannot be directly perceived, but when they come together in agglomerations, they make up the things that we can perceive with our senses. You can imagine the atoms as being like little burrs and seeds, with hooks and rough parts that allow them to join together, without losing their distinctness. When the hooks that link atom to atom become undone, then things fall apart: whether these things are cups, Greek vases, or human bodies.
In his work On Democritus, Aristotle summarised the atomist philosopher's view as follows:
[Democritus] holds that the substances are so small that they escape our senses. They have all kinds of forms and shapes and differences in size. Out of these as elements, he generates and forms visible and perceptible bodies. [These substances] are at odds with one another and move in the void because of their 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.
A Presocratics Reader, p. 112
Often it's said that Democritus's physics involves only two elements: atoms and void. But Aristotle's account makes clear that one other thing is essential for his system to work: the restless movement of atoms.
This is one reason Aristotle disapproves of Democritus. For Aristotle, nothing moves unless pushed. But Democritus makes movement one of the primary aspects of the universe. Aristotle complains that the early atomists don't give an adequate account of why and how things move.
For they say that there is always motion. But why it is and what motion it is, they do not state, nor do they give the cause of its being of one sort rather than another.
From Aristotle's Metaphysics, in A Presocratics Reader, p. 112
But perhaps for the atomists, the question isn't so much why and how things move, but instead, it is why and how it is they stay put, at least for a short while. In a restless universe, what needs to be accounted for is how things remain semi-stable, rather than how they move at all.
Laughter, mockery and good cheer
The idea that everything is at root made up of blindly clashing atoms may seem a bleak one. But Democritus was, after all, the laughing philosopher. So what was there to laugh about?
Some later commentators claimed that Democritus's laughter was a mocking laughter at the follies of human existence. But there may be another reason for Democritus's laughter. Although the remaining fragments show us that Democritus was capable of sharpness in the face of what he perceived as human folly, they don't give the sense of him as a philosopher concerned with mockery or disdain. So perhaps there was a sunnier side to Democritus's laughter. And this sunnier side may lie in his view of ethics.
For Democritus, the root of ethics is a concern with euthymia, which means “possessing a happy spirit,” or “being cheerful.” In fact, Democritus was so preoccupied with this idea of cheerfulness that he wrote a book—now lost—called On Cheerfulness.
The goal of life is cheerfulness (euthymia), which is not the same as pleasure . . . but the state in which the soul continues calmly and stably, disturbed by no fear or superstition or any other emotion
From A Presocratics Reader, p. 124
This is a powerful idea: if we understand the world as the result of the play material forces, Democritus suggests, we can be freed from superstition and from other disturbing emotions. It is an idea that the later philosopher Epicurus picks up on and develops, as we will see in a future philosopher file.
The quotes above come from A Presocratics reader: selected fragments and testimonia, edited by Patricia Curd (Hackett 2011). It is one of the best single-volume translations of the work of the Presocratic philosophers.
For a more intensely scholarly approach, try The Atomists: Leucippus and Democritus fragments, A Text and Translation with a Commentary by C.C.W. Taylor (University of Toronto Press Incorporated 1999).
Watch Theresa Doud's overview of the long history of the idea of the atom, from Democritus to the present day over on TED-Ed.
Image: Democritus, by Antoine Coypel (1692). Public Domain, via Wikimedia Commons.