Institute and Museum of History of Science, Florence, ITALY

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Paolo Casati (1617-1707) Democritus  (5th century B. C.) René Descartes (1596-1650)




Born at Abdera, in Thrace, Democritus is the most relevant figure of Greek atomism. Numerous works on differing subjects are attributed to him, the most important being the Small Cosmology. This work - gathered together, it seems, in a unique copy by the scholar Trasilo, who lived at the court of Tiberius in the mid-first century, A.D. - survives only in a few fragments. These, however, are sufficient to give us an idea of the salient points of democritean speculation.
Atoms and voids are the two fundamental concepts which support the entire democritean explanation of the physical universe. Atoms (from the Greek a-tomos "without parts") represent the prime, non-divisible building-blocks of all reality, bodies being nothing but a mass of atoms. Eternal, immutable, indivisible, impenetrable, infinite in number and their differing forms, atoms differ also in their dimensions, and, before bring our world into being, were dispersed in empty and infinite space. They lack any perceivable quality except for "size" and "geometric form". But, through our sense-organs, they produce differing sensations (colours, sounds, smells, etc.). The soul, too is, according to Democritus, a mass of atoms: "psychic" atoms, which are spherical and particularly mobile.
The atoms, moving and combining in the original void, form all of material reality, following strict mechanical laws. The motion of atoms is characterised by collisions and unforeseen changes in speed, which give rise to a series of vortices of various sizes. All bodies and an infinite series of worlds are produced from these vortices, because, according to Democritus, worlds are infinite in time and space.
Democritean atomism is historically extremely important, offering a rigorously mechanistic and deterministic model which has been enormously suggestive throughout the course of history of science and Western philosophy.





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