Or, because running into heavy objects is a good intuition pump:
Reality is what trips you up when you run around with your eyes closed.
I think this was in a book by James P. Hogan, but a bit of Googling only reveals one or two other people quoting it but not remembering where it came from.
Or, because running into heavy objects is a good intuition pump:
I think this was in a book by James P. Hogan, but a bit of Googling only reveals one or two other people quoting it but not remembering where it came from.