Keep the ass to the chair. Everything has been thought before, but the problem is to think of it again.
All models are wrong but some are useful.
Far better an approximate answer to the right question, which is often vague, than an exact answer to the wrong question, which can always be made precise. The paradox is now fully established that the utmost abstractions are the true weapons with which to control our thought of concrete fact. I guess I'll have to learn it, though. It's an invention of the devil. To be is to classify is to act, all of which means throwing away information.