• At any one time there is a natural tendency among physicists to believe that we already know the essential ingredients of a comprehensive theory . But each time a new frontier of observation is broached we inevitably discover new phenomena which force us to modify substantially our previous conceptions. I believe this process to be unending, that the delights and challenges of unexpected discovery will continue always.

    "Les Prix Nobel" ("The Nobel Prizes 1980") edited by Wilhelm Odelberg, Nobel Foundation, Stockholm, 1981.