Howard Gardner's theory of multiple intelligences bears forth at least one keen insight. Interpersonal intelligence (the ability to understand the needs and motivations of others) is very different from Intrapersonal intelligence (the ability to understand one's own needs and motivations). Yeah, maybe it's an obvious point -- psychoanalytically obvious, even -- but still. A little detail on the interplay between the two (and a close charting of persons with various degrees of each) would make for good reading.