The atomic theory of matter asserts that material bodies are made up of small particles. This theory was founded in ancient times by Democritus and expressed in poetic form by Lucretius. This view was challenged by the opposite theory, according to which matter is a continuous expanse. As quantitative science developed, the study of nature brought to light many properties of bodies which appear to depend on the magnitude and motions of their ultimate constituents, and the question of the existence of these tiny, invisible, and immutable particles became conspicuous among scientific enquiries
