Answer:
Democritus believed that all natural substances were made of atoms.
Democritus was an ancient Greek philosopher who lived around the 5th century BCE. He is known for his theory of atomism, which proposed that all matter is composed of indivisible particles called atoms.
According to Democritus, atoms are eternal, unchangeable, and constantly in motion. He believed that these atoms are the fundamental building blocks of all matter and that they combine and interact to form different substances.
Democritus' atomic theory was a significant departure from the prevailing philosophical views at the time, which proposed that matter was infinitely divisible. His idea of atoms laid the groundwork for modern atomic theory, which was further developed by scientists such as John Dalton in the 19th century.
In summary, Democritus believed that all natural substances were made of atoms, which are the smallest indivisible particles of matter.