Even if scepticism does not subvert life, surely it will subvert science? The Hellenistic period was the
golden age of Greek science, and it is natural to wonder whether the scientists noticed the concerns and
perplexities of their philosophical contemporaries.
Euclid's Elements are perhaps the most celebrated product of the period. Euclid (ft.c. 300) 'composed his
Elements by systematizing much of the work of Eudoxus and completing much of that of Theaetetus,
putting into irrefutable demonstrative form propositions which had been somewhat loosely proved by his
predecessors'. Euclid's achievement lay in form rather than in content: he insisted on a rigorous and
systematic presentation of mathematical theorems. Archimedes of Syracuse (287-212) and Apollonius of
Perge {ft. c. 200) opened up new areas of mathematical knowledge. 'His contemporaries called
Apollonius a great geometer because of the remarkable features of the theorems on cones which he
proved,' and modern scholars judge his work on conic sections one of the masterpieces of Greek
geometry. Archimedes' was a more universal talent: he did original work in astronomy and engineering as
well as in mathematics. Within mathematics he excelled in geometry (where he calculated the
approximate value of pi), in mechanics (where he developed statics and invented hydrostatics), in
arithmetic (where he discovered ways of calculating with very large numbers).
Astronomy is a mathematical science, and both Archimedes and Apollonius were astronomers. Early in
the third century Aristarchus of Samos (fl. c. 275) 'hypothesized that the fixed stars and the sun stay
motionless, and that the earth moves in a circle about the sun which lies at the centre of its orbit.' But
Aristarchus' innovative hypotheses were not developed by his successors, who returned - in part for good
scientific reasons - to a geocentric model of the universe. Apollomus was the first to devise a system of
epicycles and eccentric orbits: the system was elaborated by Hipparchus of Nicaea (fl. c. 135), the second
astronomer of the age, and it reached its zenith of sophistication in the work of Ptolemy some three
centuries later. Hipparchus was also an empirical astronomer: he invented or improved various optical
aids; he produced a star-map; he discovered the precession of the equinoxes. Beside Hipparchus, the
polymath Eratosthenes of Cyrene (fl. c. 225) cuts a small figure - indeed, 'because he was second best in
every branch of study ... he was nicknamed Beta'. But he merits mention here for his calculation of the
circumference of the earth: his method was sound, and his result was astonishingly accurate.