The idea that everything is made up of a few simple parts originated during the 400's B.C., in the philosophy of atomism. Atomism was founded by which Greek Philosopher?

Leucippus (5th century BC) is credited as the founder of atomism, though his student Democritus developed and popularized the theory. Lucretius was a Roman poet who later wrote about atomism, and Epicurus adopted atomist philosophy but didn't found it. Many textbooks incorrectly attribute atomism's founding solely to Democritus.