For God’s sake, please give it up. Fear it no less than the sensual passion, because it, too, may take up all your time and deprive you of your health, peace of mind and happiness in life.
So said Wolfgang Bolyai, urging his son Janos Bolyai to give up work on hyperbolic geometry, as quoted in David W. Henderson and Daina Taimioa’s “Crocheting the Hyperbolic Plane,” the updated version of which is published in Mathematical Intelligencer, Vol. 23, No. 2, pp. 17-28, Spring 2001.
(Thanks to investigator Dave Brooks for bringing this to our attention.)