The particles of chemical matter for which chemists and other natural philosophers of the early 19th century found experimental evidence were thought to be indivisible, and therefore were given the name "atom", long used by the atomist philosophy.

However, in the 20th century, the "atoms" of the chemists were found to be composed of even smaller entities: electrons, neutrons and protons, and further experiments showed that protons and neutrons are made of quarks.

This in turn meant that motion is impossible, because there is no void to move into.

Although the connection to historical atomism is at best tenuous, elementary particles have thus become a modern analog of philosophical atoms, despite the misnomer in chemistry.

Philosophical atomism is a reductive argument: not only that everything is composed of atoms and void, but that nothing they compose really exists: the only things that really exist are atoms ricocheting off each other mechanistically in an otherwise empty void.

While organisms may feel hot or cold, hot and cold actually have no real existence.

They are simply sensations produced in organisms by the different packings and scatterings of the atoms in the void that compose the object that organisms sense as being "hot" or "cold".

In Plato's Timaeus, the character of Timeaus insisted that the cosmos was not eternal but was created, although its creator framed it after an eternal, unchanging model.

One part of that creation were the four simple bodies of fire, air, water, and earth.

) is a natural philosophy that developed in several ancient traditions.

The atomists theorized that nature consists of two fundamental principles: atom and void.

On the other side was Parmenides, who believed instead that all change is illusion.

Parmenides denied the existence of motion, change and void.

But Plato did not consider these corpuscles to be the most basic level of reality, for in his view they were made up of an unchanging level of reality, which was mathematical.