Final answer:
Leucippus and Democritus theorized that matter was composed of indivisible, finite particles called 'atomos.' They explained different physical properties through differences in atoms' shapes and sizes. However, Aristotle's contrary view that matter was composed of divisible elements stalled the development of atomic theory for two millennia.
Step-by-step explanation:
The 'Basic Idea' about Matter by Leucippus and Democritus
The basic idea about matter proposed by Leucippus and Democritus is that all matter is composed of small, finite, and indivisible particles called 'atomos', which means 'indivisible' in Greek. These atoms differ in shape and size and can join together to form different substances.
Explanation of Different Physical Properties
Leucippus and Democritus used the concept of atoms to explain different physical properties by suggesting that the variety in shape and size of atoms could account for the diversity of matter in the natural world.
Reception by Aristotle and Impact on Atomic Theory Progress
The ideas of these philosophers were not well received by Aristotle, who believed that matter consisted of various combinations of four 'elements' - fire, earth, air, and water - and could be infinitely divided. This Aristotelian view dominated for the next 2,000 years, resulting in the stagnation of atomic theory during that period.