History II
Plato
• Circa 427 –347 BC
Athens
• Greek mathematicians had proven that the
sum of the angles of a triangle is 180° exactly.
• Nothing made by man is exact.
• Theory of Forms
• Not Christian, but
• His student: Aristotle
Aristotle
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The Nature of Things
Horses were naturally like horses.
Heavy things naturally fall faster.
Moving objects naturally came to a halt.
The heavens were heavenly.
Stars moved in the most perfect shape: circle
Plato’s Forms
• Student: Alexander the Great
Alexander the Great
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356 –323 BC
Age 20: Succeeded his father to the throne of Macedonia
Age 30: Conquered most of the known world
Age 32: Died
His generals fought civil wars. The Empire
broke apart, each general taking a piece
Alexandria
Egypt
• Ptolemy I Soter - Alexander’s General
323 BC Won Egypt
• Claudius Ptolemy
c. AD 90 – c. AD 168
• The Planets “wander”
• Epicycles:
Circles upon circles
Copernicus 1473 – 1543
• Polish Cleric
• c 1439 Printing press
developed by Gutenberg
• 1543 Copernicus publishes
De revolutionibus
• Less Epicycles if the Sun is
the Center
• The Inquisition
Galileo
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First person to look at the sky using a telescope.
Looked at the moon and saw craters
Looked at Jupiter and saw 4 moons orbiting
Publicly stated his support for Copernicus in the
vernacular.
Called before the Inquisition.
Recanted
“Eppur si muove”
Sentence: House Arrest