Prodicus of Ceos, the Greek Sophist, was probably born before 460 BCE and was still alive at the time of the death of Socrates in 399 BCE. He traveled widely as an ambassador for Ceos and also earned a great deal of money lecturing in various Greek cities, especially in Athens. His writings are known to have dealt with physical doctrines, with religious and moral themes, and above all with distinctions between the meanings of words usually treated as synonyms. Socrates attended a lecture by him on the last of these topics and regularly claimed to be a pupil of Prodicus in the art of synonymy (Protagoras 341A, Meno 96D).

In physics he appears to have treated the four elements of Empedocles as divine, and no doubt they formed the basis of the cosmology of Prodicus, to which Aristophanes refers in the Birds (1.692), although the fanciful...