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Although Democritus is often fully credited with the idea of atomic thought, it was actually his mentor, Leucippus, who first introduced the concept. In the 5th century BC, Democritus organized the views of Leucippus while adding his own. The word "atom" is derived from the Greek word "atomos," and it has been translated as either "uncuttable" or "indivisible." Democritus reasoned there must be a point at which an atom could not be divided in half. This would be akin to slicing a piece of paper in half as many times as possible, except on a microscopic level.
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Atomic theory was not looked upon favorably by the philosophical community at the time. More specifically, Aristotle and Plato argued strongly that atoms, i.e. matter, could indeed be divided indefinitely. They were the "popular" philosophers of the day, so Democritus' and Leucippus' ideas were generally discredited. Furthermore, there was no solid, experimental proof to back this novel claim. Thus, it was a purely philosophical debate devoid of any empirical evidence, and the debate fell in limbo for over 2000 years.
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