My father had from the earliest days instilled into me the knowledge that I was to work and to make my own way in the world, and I had always supposed that this meant that I must enter business.

But in my freshman year (he died when I was a sophomore) he told me that if I wished to become a scientific man I could do so.

He explained that I must be sure that I really intensely desired to do scientific work, because if I went into it I must make it a serious career; that he had made enough money to enable me to take up such a career and do non-remunerative work of value _if I intended to do the very best work there was in me_; but that I must not dream of taking it up as a dilettante.

He also gave me a piece of advice that I have always remembered, namely, that, if I was not going to earn money, I must even things up by not spending it.

As he expressed it, I had to keep the fraction constant, and if I was not able to increase the numerator, then I must reduce the denominator.