Who was Democritus? What was Democritus best known for?


Who is Democritus, one of the ancient Greek scientists and philosophers, who defined the atom for the first time? Information about the life of Democritus.

Democritus of Abdera (c. 460-370 BC) was a Greek philosopher, also known as the “laughing philosopher” or “the laughing philosopher”, for having the tendency to laugh at the world and its problems. One of his main contributions to philosophy and science was atomism, understanding that the universe is made up of millions of tiny particles.


Despite being a contemporary of Socrates, Democritus’ line of thought is located in the pre-Socratic period, since his philosophical approach was more similar to that of the pre-Socratic thinkers than to that of Socrates and Plato. Democritus’ works cover various areas, including ethics, physics, mathematics , music, and cosmology. Most of these works have survived thanks to secondary sources, such as the criticisms of Aristotle .


Democritus Biography

The name Democritus means “chosen of the people.” This philosopher was known not only by name, but also by nicknames. He was called the Abderita, Milesio, or the “laughing philosopher.”


When his father died, Democritus received the inheritance that he had left him. With that money, he traveled and studied in Persia (where he was a student of the scholars and magicians of King Xerxes I), Babylon, India, Ethiopia, Egypt and Greece.

Once the inheritance was exhausted, he returned to his homeland and settled with his brother Damosis. Here he focused his studies on natural philosophy, which he taught through public classes. He was a disciple of Leucippus, with whom he founded the school of atomism.


His studies took place while the military campaign was carried out by Xerxes I against the Greeks, in an event known as the Medical Wars, which would  end with the conquest of the Achaemenid Empire by Alexander the Great. Democritus is said to have lived extravagantly, which is why he is credited with numerous stories that take place in the different places he visited, including Egypt, Persia, and Mesopotamia .

There are also stories that tell that Democritus used to laugh ironically at the way human beings coped with the advances of the world. He often laughed, arguing that laughter makes men wise.


Democritus is believed to have died in 370 BC at the age of 90. However, many authors of the time agree that he lived more than a hundred years, and chose to end his life voluntarily.

Philosophy of Democritus

In the context in which Democritus was developed, the priority was not the empirical approach but logic, and the need to arrive at conceptions solely through rationality. This is explained because these philosophers downplayed everything that was perceived through the senses, to which they did not grant reliability characteristics. They, including Democritus, thought that sensory perception was highly relative.



One of the most relevant contributions of Democritus was the creation of the philosophical school of atomism. This line of thought arose in response to what was raised by Parmenides, who affirmed that matter is immutable and eternal, and that the changes that our senses observe are errors of perception.

In this sense, Democritus and Leucippus pointed out that there were, in fact, certain immutable materials, which were combined in different ways to give rise to the changes that we observe in matter. These “immutable materials” were called “atoms,” which means “indivisible” in Greek.

According to the atomistic school, atoms are tiny, solid particles that vary in size, mass and shape and that move in a repellent vacuum. When they collide with each other, they form conglomerates that give rise to other more complex materials.

This means that the macroscopic objects that we observe every day are actually clusters of small atoms. Democritus’ theory of atoms was correct in many respects, but it was rejected by philosophers. However, it influenced the development of modern atomic theories, such as Dalton’s atomic theory.

Atomic theory

Within the framework of the atomistic school, Democritus is credited with developing the atomic law of the universe. This law had been conceived long ago by his teacher, the philosopher Leucippus. The main elements of this theory can be summarized taking into account the following points. First, atoms have five specific characteristics: the first of these is that they are indivisible, that is, they can never be separated.

The second characteristic is that they are eternal, enduring in time, without beginning or end. The third peculiarity refers to the fact that they are incompressible, they have specific shapes and sizes, so they cannot be compressed.

The fourth characteristic is related to its homogeneity; Although they can present certain differences in terms of shapes and forms, the atoms are homogeneous in terms of their interior composition.

Finally, the fifth characteristic that Democritus assigned to atoms is that they are invisible. It is not possible to see them, because they are infinitely small, not perceptible to the human eye; We only have the possibility to access the result of the combination of several of these.

In addition, for Democritus the different configurations and combinations that were generated from the atoms differed from each other in terms of the properties of the element produced. That is, different compositions generated different properties.

Relationship with god

From what has been explained previously, it can be deduced that Democritus did not consider God (or the gods, remember that the Greeks were polytheists) within what makes up the world, which is why this philosopher is considered the first atheist in history, thus as the first thinker with a materialistic character.


For Democritus, matter was not created by God, but by itself. He assumed that all the modifications that the beings presented were due to physical issues, not supernatural elements or actions. In fact, a fundamental aspect of the theory proposed by Democritus has to do with the conception of chance as the basis for understanding the world. This philosopher establishes that both necessity and chance constitute the elements from which all processes are generated.


The doctrine of Democritus and Leucippus had an important consideration on the movement. Until now, movement had been conceived as a phenomenon that was generated in a timely manner, as a consequence of a specific action. Instead, Democritus established that movement is an element that exists in itself, and was even one of the first to introduce the concepts related to what we know today as inertia.


This concept of Democritus, associated with not being, was in turn considered a non-absolute entity. This is so because it considers that the vacuum was the stage in which the free particles, unrelated to each other, moved. Democritus established that the vacuum is also present in matter, as he considered that each atom was characterized by a particular shape, which allowed it to link with others to generate a specific element.

Combination, not fusion

This union of atoms was only combination, not fusion, because these particles always remained as different elements from each other.

Then, according to Democritus, within these newly formed elements as a consequence of the mixture of atoms there is also a small portion of vacuum that contributes to the differentiation of each atom. In fact, the vacuum is the space that allows the atoms to be in constant motion and that gives it the characteristic of eternity.

Democritus established that atoms unite to generate new elements. As a consequence of a collision between these elements and others, the atoms separate again and later combine with others to form new elements, and so on. So, without the existence of a vacuum, the atoms would not have that ideal scenario to unfold and rejoin with others, to form new combinations.

“The highest good”

In terms of ethics, Democritus followed a philosophy similar to hedonism, so much so that it could be considered its predecessor. He was one of the first philosophers to propose the existence of a “supreme good” or goal, which he called “good humor” or “joy”.

This good humor was directly related to the human being’s ability to enjoy life without having to worry about the problems that surround it.

Likewise, he pointed out that this state of well-being was achieved through the moderate pursuit of pleasures, distinguishing two types: useful and harmful pleasures, the useful ones being those that generated joy. Democritus is credited with the phrase “the brave man is he who conquers not only his enemies but his pleasures.”

Contributions to philosophy and science


Although Democritus is better known thanks to his atomistic theory and his philosophical studies, he was also a renowned geometrist. In fact, this science was one of the ones that he taught the most to those who followed him and many of his publications – which unfortunately have not survived – were related to the field of geometry and astronomy.


His interest in geometry can be understood by looking at the context of the time, as many philosophers believed that the vast majority of events and situations that occurred in the world could be explained through geometry and arithmetic.

This is evidenced by the fact that Democritus even gave characteristics of geometric figures to abstract elements, such as smell or taste. In this sense, he associated some shapes with certain elements, which meant that they tasted like this or that.

For example, for Democritus the elements that were rounded and smooth were characterized by having a bitter taste; likewise, substances that were rather circular had a sweeter taste, and all those acidic and sour elements had a sharp and angled structure. These interpretations, which were also applied in other areas, such as touch, attest to how elementary he considered geometric shapes.

Study of volumes

In addition, his studies also include various treatises related to the volume of figures. For example, according to historical records, it is believed that Democritus may have found the formula that reflects the volume of a pyramid, and that he also discovered that the same formula can be applied in the case of wanting to identify the volume of a cone.

Two main theorems emerged from these dissertations that are attributed to Democritus. The first of these theorems indicates that, when comparing a cylinder and a cone that have equal height and base, the volume of said cone will be one third of the volume of said cylinder.

The second theorem attributed to Democritus indicates that, having a pyramid and a prism that measure the same and have the same base, the volume corresponding to the pyramid will be one third of the volume of the prism.

Dissertations on light

As has been seen, Democritus was a philosopher who focused on understanding the why of things based on the physical field, giving special importance to matter and its composition.

Therefore, the concerns that he presented were related to giving a physical explanation to different phenomena. One of these was light and its corpuscular nature. Following his reasoning, Democritus identified himself with the emission theory, which indicates that the eyes produce a kind of rays or particles, thanks to which it is possible to perceive and distinguish objects.

Theory of perception

Democritus’ theory of perception is closely related to the school of atomism. This philosopher pointed out that the images ( eidôla) were actually layers of atoms.

These films of atoms shrink and expand. Only those that shrink enough are able to enter the human eye. In this sense, it is the changes produced in the films of atoms that allow us to perceive reality. Also, the visible properties of macroscopic objects (such as size and shape) are the product of these films.



In terms of epistemology, Democritus distinguished two types of knowledge: bastard knowledge and legitimate knowledge. Bastard knowledge is that subjective and insufficient, which is obtained through sensory perception.

For its part, legitimate knowledge is genuine knowledge, which is obtained through the processing of bastard knowledge, using inductive reasoning .

A primitive anthropology

Although there is no conclusive evidence, some historians point out that Democritus may have been the originator of the theory about the historical development of human communities. This assumption is made taking into account the information obtained through secondary sources, according to which Democritus showed interest in the study of the origin of human societies, their institutions and their culture. 

Mathematics and geometry

Democritus was one of the pioneers in mathematics and geometry. In fact, he wrote treatises on numbers, figures, tangents, irrational numbers, among others. However, nowadays there are no copies of these treatises and they are known only from secondary sources.

Similarly, it is known that Democritus was the first to observe that the volume of a cone is equal to one third of the volume of a cylinder that has the same base and the same height as the cone in question.


Democritus was also the first philosopher to realize that the celestial body we know as the Milky Way was formed by the light of thousands of distant stars. He was also one of the first to argue that the universe was full of planets, some of which were uninhabited. 

Works of Democritus

The work of Democritus was unknown in Athens. Aristotle is believed to have been the first to study and comment on it extensively, and that the reason his work was not as famous as that of other philosophers is because he himself was not interested in being famous.

After his death, the Greek historian Diogenes Laercio would speak about the existence of multiple writings left by Democritus. These writings would include more than 70 texts and treatises on mathematics, ethics, physics, technique and music.

Among his most famous works are the Great Diacosmos , and several compilations of fragments of his thoughts, such as those by Leszl, Diels-Kranz and Luria. Due to the content of his work, Democritus is considered one of the first encyclopedic authors in history.


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