Greek philosophers
Leukippos of Miletus
Leukippos of Miletus was a Greek philosopher who was born in 500 BC in Miletus and died in 440 BC. He was the founder of atomism and the predecessor of Democritus.
None of Leukipp's works have survived, although we know 7 titles of his books. His ideas, however, passed into the work of his more famous successor, Democritus. And so it is often difficult to determine which view is whose, because they were quite identical. It even caused Epicurus to doubt its existence. However, Aristotle and Theophrastus of Lesbos explicitly name Leucippus as the originator of atomism.
Leukippos formulated the law of causality. It states that "nothing comes into being by chance and everything has a reason".
Within the framework of atomism, he determined that matter consists of a large number of homogeneous small particles moving in the void or space. They are the simplest parts of matter, they cannot be subdivided, they do not come into existence or cease to exist, and they are not subject to any influences. He named them atoms, after the Greek word "atomos", meaning "extremely small" or "indivisible".