Democritus hypothesized that all matter (plus space and time) is composed of tiny indestructible units, called atoms, which are eternal, invisible, they entirely fill up empty space that they lie in, and so small that they can’t be divided. This idea seems motivated by the question of how finely one can go on cutting up matter. While Democritus performed no experiments and had only the slightest evidence for suggesting the existence of atoms, his theory was kept alive by the Roman poet Lucretius, who originally initiated the atomic theory that Democritus developed further. Early atomic theory stated that the characteristics of an object are determined by the shape of its atoms. For example, solids are made of small, pointy atoms, liquids are
