Euclidean Geometry

Euclid (~ 325 to ~265 BC) is called the Father of Geometry, not because he invented it, but because his book Elements is the oldest geometry text we have in the western world today.

Euclid believed each part of geometry should be based on previously proven parts. However, something has to be the starting point, and he proposed four undefined terms and five basic axioms. The rest of Euclidean geometry is based upon these basic building blocks.

The fifth axiom, called the parallel postulate, has been very controversial. More complex than the other four, many mathematicians tried to prove it using the other axioms. Failure to do so developed into the existence of non-Euclidean geometries.