Epicurus - Greek philosopher; founded the system known as Epicureanism.He studied with followers of Plato and Democritus before opening his school in Athens.Plato - Greek philosopher; pupil of Socrates; dealt with the nature of the universe; developed atomic theory of chemical change; ascribed geometric forms composed of bounding planes to the elements of earth, fire, air and water based upon their physical properties; held that elements could convert into one another through rearrangement of bounding planes; used deductive reasoning as a learning method.

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He also played an importqant role in the development of the Western or Sicilian school of Greek medicine.

He cured a plague at the Sicilian city of Selinus and claimed he was a god.

Empedocles - Some suggest (c.484-c.424) - Greek doctor, poet and philosopher.

To account for real change, he assumed that there must be more than one kind of matter, and he postulated four roots as elements; earth, air, fire, and water.

His theory that the earth exerted a magnetic influence throughout the solar system was a precursor to the modern conception of gravity as an attracting force between masses.

Gilbert was among the first to divide substances into electrics (spar, glass, amber) and nonelectrics.

The Reformation, the Renaissance, and the scientific period of the 17th century can hardly be contemplated without printed books.

Nicholas Copernicus - Polish astronomer; regarded the founder of modern astronomy. He studied mathematics and optics at Cracow, then canon law at Bologna, before becoming canon of Frombork.

The treatise was translated into English in 1912 by future U. president Herbert Hoover and his wife, Lou Henry Hoover. He became a devoted follower of Erasmus, who wrote a foreward to Agricola's first book on mining and metallurgy (1930).

While town physician of Joachimsthal (now Jachymov, Czech Republic), he became intensely interested in all aspects of the mining and metallurgy industry by which the town thrived and began a 25-year study of the subject, which culminated in hos posthumously published masterpiece.

Heraclitus - Greek philosopher; first of the Greeks to develop a theory of the human soul; he praised its creative resources and spoke of the importance of self-exploration; he spoke of the logos that is common to all and said that the universe is ruled by logos; he always urged that close attention be given to the polarites and concealed structures emodied in language.