Richard Feynman (1918–1988) American theoretical physicist
from a 1987 class, as quoted in David L. Goodstein, "Richard P. Feynman, Teacher," Physics Today, volume 42, number 2 (February 1989) p. 70-75, at p. 73
Republished in the "Special Preface" to Six Easy Pieces (1995), p. xx.