Intelligence and IQ

What French mathematician, born on this day in 1906, stated in his book, The Apprenticeship of a Mathematician:

 Every mathematician worthy of the name has experienced … the state of lucid exaltation in which one thought succeeds another as if miraculously… this feeling may last for hours at a time, even for days. Once you have experienced it, you are eager to repeat it but unable to do it at will, unless perhaps by dogged work..