I am coming more and more to the conviction that the necessity of our geometry cannot be demonstrated, at least neither by, nor for, the human intellect. . . . Geometry should be ranked, not with arithmetic, which is purely aprioristic, but with mechanics.
Karl Friedrich Gauss (1777 - 1855)
Source: Quoted in J. Koenderink Solid Shape, Cambridge Mass.: MIT Press, 1990.
Contributed by: Zaady