I believe that no endeavor that is worthwhile is simple in prospect; if it is right, it will be simple in retrospect.

Edward Teller (1908-2003) Hungarian-American theoretical physicist

Quoted by Judith Shoolery, personal communication (2004)
    (Source)

Quoted in István Hargittai, The Martians of Science: Five Physicists Who Changed the Twentieth Century (2006).