Aesthetics - rather than reason - shapes our thought processes. First comes aesthetics, then logic. 'Thinking in Numbers' is not about an attempt to impress the reader but to include the reader, draw the reader in, by explaining my experiences - the beauty I feel in a prime number, for example.
I know from my own experience that there is much more to 'intelligence' than an IQ number. In fact, I hesitate to believe that any system could really reflect the complexity and uniqueness of one person's mind, or meaningfully describe the nature of his or her potential.
I think if I ever stopped pushing myself, I would revert quickly to quite repetitive, restrictive behaviour. But in pushing myself and concentrating on what I can do, I think I can contribute to society. And that gives me the desire to keep pushing, to see what I'm capable of. The thing to do is not to stop.