Genius is eternal patience.

Lord, grant that I may always desire more than I can accomplish.

If a man is called to be a streetsweeper, he should sweep streets even as Michelangelo painted, or Beethoven played music, or Shakespeare wrote poetry. He should sweep streets so well that all the hosts of heaven and earth will pause to say, here lived a great streetsweeper who did his job well.

An expert is a man who has made all the mistakes, which can be made, in a very narrow field.