>>13430886Based Euclid. Flat is justice! Cow tits not welcome.
>>13431157>>13431166Menelaus of Alexandria, a few decades before Ptolemy.
>>13431284>Before the 19th century this kind of "model-thinking" didn't existThe ancient Greeks actually had a rough idea of the concept of geodesic. Their books on spherical geometry come very close to being treatises of two-dimensional non-Euclidean geometry. They never made that leap more because of a philosophical prejudice than for a lack of conceptual tools.
>>13433293>>13433615The equivalent of a straight line on a sphere is a great circle. Given two points on a sphere there is one and only one great circle joining them; this circle is determined by the two points on the sphere and by the center of the sphere. Since given three points there is one and only plane through them, the great circle passing two given points on a sphere is unique, and the smaller arc of this circle is the shortest distance between the two points on the sphere. Circles of latitude (unlike those of longitude) don't pass through the center of the sphere (except for the one passing through the equator) so they are not great circles. All great circles meet at two points on the sphere, so there are no parallels.
