If you are with the quality, or at a funeral, or trying to go to sleep when you ain't sleepy - if you are anywheres where it won't do for you to scratch, why you will itch all over in upwards of a thousand places.
It's an epitome of life. The first half of it consists of the capacity to enjoy without the chance; the last half consists of the chance without the capacity.
That is the way of the scientist. He will spend thirty years in building up a mountain range of facts with the intent to prove a certain theory; then he is so happy with his achievement that as a rule he overlooks the main chief fact of all-that all his accumulation proves an entirely different thing.