"For each phase of life, we can say that, given otherwise equal conditions, those blessed with better cognitive abilities profit both more quantitatively and qualitatively from the stimulation and instructions in their environment (e.g., in school) that those with less favorable abilities.

In our societies, those who possess better intellectual abilities and have received better education generally reach greater opportunities to gain an occupational and social position that provides additional cognitive stimulation in turn.

Those who are more intelligent and more successful in their careers often develop a greater degree of self-confidence. As a result, they are willing to invest more effort in solving difficult problems, thus increasing their probability of success."