Λεύκιππος was an ancient Greek philosopher, often considered one of the founders of the atomic theory. He lived in the 5th century BCE and is believed to have been a teacher of Democritus, who further developed his ideas. Λεύκιππος proposed that everything in the universe is made up of small, indivisible particles called atoms. His work laid the groundwork for later scientific thought, influencing both philosophy and natural science. Although few of his writings survive, Λεύκιππος's ideas challenged the prevailing notions of matter and change, paving the way for future philosophers and scientists to explore the nature of reality.