What is the theme in Buffett: The Making of an American Capitalist by Roger Lowenstein?

Intelligent investment is a major theme. Despite Buffett's rather consistent and pervasive success, Wall Street "big boys" have continued to attribute these accomplishments to luck or chance. They posit that Buffett has simply been one of those "blessed" investors who, by randomness, has managed to pick winners. Buffett, however, insists that his financial fortune is the result of very specific axioms which he has practiced throughout his investment career.