“If man’s thinking is to be valid, this process must be guided by logic, ‘the art of noncontradictory identification’—and any new concept man forms must be integrated without contradiction into the hierarchical structure of his knowledge. To introduce into one’s consciousness any idea that cannot be so integrated, an idea not derived from reality, not validated by a process of reason, not subject to rational examination or judgment—and worse: an idea that clashes with the rest of one’s concepts and understanding of reality—is to sabotage the integrative function of consciousness, to undercut the rest of one’s convictions and kill one’s capacity to be certain of anything.”

in Nathaniel Branden, Objectivism, Writers