Pythagoras (6th century BC)
Realized the earth was a sphere and established the numeral basis of musical harmonics.
Empedocles (c. 490-430 BC)
Held that all matter consisted of four elements.
Hippocrates (c.460-c.377 BC)
Became known as ‘the father of medicine’.
Euclid (fl.c.300 BC)
Set out the principles of geometry.
Aristarchos of Samos (c.310-230 BC)
Realized that the earth rotates about its own axis and orbits the Sun.
Archimedes (c.287-c.212 BC)
Pioneered the field of mechanics and invented many ingenious devices.
Eratosthenes of Cyrene (c.276-c.194 BC)
Calculated the circumference of the Earth with a creditable degree of accuracy.
Source: World History, 50 key milestones by Ian Crofton