“Norbert A’Campo of the University of Basel once asked Grothendieck about something related to the Platonic solids. Grothendieck advised caution. The Platonic solids are so beautiful and so exceptional, he said, that one cannot assume such exceptional beauty will hold in more general situations.”

(Allyn Jackson’s “Comme Appelé du Néant— As If Summoned from the Void: The Life of Alexandre Grothendieck”, Notices of the AMS, vol. 51, no. 10, November 2004, p. 1194.)