Editing Posidonius (section)

===Mathematics===
Posidonius was one of the first to attempt to prove [[Parallel postulate|Euclid's fifth postulate of geometry]]. He suggested changing the definition of parallel straight lines to an equivalent statement that would allow him to prove the fifth postulate. From there, Euclidean geometry could be restructured, placing the fifth postulate among the theorems instead.<ref>Trudeau, Richard. ''The Non-Euclidean Revolution'', Boston: Birkhauser, 1987, pp. 119–120.</ref>

In addition to his writings on geometry, Posidonius was credited for creating some mathematical definitions, or for articulating views on technical terms, for example 'theorem' and 'problem'.