I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose... the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order... It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.
That's utter BS, imo. The brain has no shortage of space, as can be seen by savants that can learn whole libraries by heart and still learn more. Of course, it is important not to have a bunch of random facts at the front of your awareness during everyday life, but that does not mean you should not look beyond your own nose, or that it is in fact harmfull to aquire skills you can't apply in your current profession, which this quote implies.
Testen Sie Ihre Fähigkeiten, machen Sie den Schreibtest.