*Never take down a fence before you know why it was put up in the first place."
I'm still not sure I agree with it, since it sounds like rationalization for "We've always done it this way."
EDIT: All of your responses are correct, and I appreciate knowing where the quote/paraphrase comes from. Unfortunately, the unique environment I'm in means that this paraphrase is aimed at the type of people (warehouse workers) who would most certainly read into it as a cop-out, and not the nuanced and thoughtful call to rational thinking that it is.
I can't find a date for the Frost quote, though. not sure who was first (they were actually born the same year, so either is possible).
It merely means that you should ask people 'why do we do this' until you get a better answer than 'We have always done it this way' (unless the actual answer is that).
It is a good warning to heed too -- otherwise you will end up redoing all the mistakes of the past.