Final answer:
Democritus was the first philosopher to propose the idea of atoms, describing them as tiny, indivisible units of matter.
Step-by-step explanation:
The first person to propose the idea of atoms was Democritus. Along with his mentor Leucippus, Democritus theorized that the universe is composed of tiny, indivisible, and solid objects which they termed atomos, meaning 'uncuttable' or 'indivisible' in Greek. While other Greek philosophers like Aristotle believed in a continuous matter, Democritus introduced the concept that matter is composed of atomos, a revolutionary idea that laid the groundwork for modern atomic theory.