### „There is no branch of mathematics, however abstract, which may not some day be applied to phenomena of the real world.“

— Nikolai Ivanovich Lobachevsky Russian mathematician of Ukrainian origin 1792 - 1856

As quoted in George Edward Martin, The Foundations of Geometry and the Non-Euclidean Plane, Springer (1998 [1975]), p. 225; also in Stanley Gudder, A Mathematical Journey, McGraw-Hill (1976), p. 36.