> 'Why do you dance?' Dirac asked [Heisenberg]. 'When there are nice girls, it is a pleasure,' Heisenberg replied. Dirac pondered this notion, then blurted out:

> 'Why do you dance?' Dirac asked [Heisenberg]. 'When there are nice girls, it is a pleasure,' Heisenberg replied. Dirac pondered this notion, then blurted out: 'But, Heisenberg, how do you know beforehand that the girls are nice?'" The difference between a theoretician and a scientist. Heisenberg was clearly the scientist.