Does the Fano plane mnemonic for octonion multiplication have any deeper meaning? http://upload.wikimedia.org/wikipedia/commons/2/2d/FanoPlane.svg The symmetry group of the Fano plane is PSL(2,7), the second-smallest nonabelian simple group. It is also the smallest Hurwitz group, and the group of automorphisms of the Klein quartic. http://en.wikipedia.org/wiki/PSL(2,7) I guess I'm wondering if Hurwitz' classification of normed division algebras and Hurwitz' theorem on automorphisms of Riemann surfaces are directly related in some way. <http://en.wikipedia.org/wiki/Hurwitz%27s_theorem_(composition_algebras)> <http://en.wikipedia.org/wiki/Hurwitz%27s_automorphisms_theorem>