A wonderfully accessible piece on the hyperbolic plane.
Crocheting the Hyperbolic Plane: An Interview with David Henderson and Daina Taimina Margaret Wertheim
"For God's sake, please give it up. Fear it no less than the sensual passions, because it, too, may take up all your time and deprive you of your health, peace of mind and happiness in life."
- Wolfgang Bolyai (1775-1856) to his son Janos Bolyai regarding the study of hyperbolic geometry