Looking back now on the long path my life has followed, on the lives of my peers and colleagues, and on the briefer ones of the young recruits who have worked with us, I have become persuaded that, in scientific research, neither the degree of one's intelligence nor the ability to carry out one's tasks with thoroughness and precision are factors essential to personal success and fulfillment. More important for the attaining of both ends are total dedication and a tendency to underestimate difficulties, which cause one to tackle problems that other, more critical and acute persons instead opt to avoid.