This is one of my favorite quotes.
A symbol...is an object of perception that is innately linked to a pattern of meaning. A sign...is an object of perception that has an arbitrary set of concepts assigned to it. The meaning of a symbol comes from the symbol's participation in the world of meaning and cannot be changed in any real way without changing the symbol itself at the deepest of levels. The meaning of a sign, by contrast, comes from nothing more than an agreement among those who make use of it. Equally, the meanings of a sign can normally be defined exactly, however complex the meaning may turn out to be. The meanings of a symbol, on the other hand, cannot be defined in so precise a way. They can be suggested and outlined, but because the symbol participates in a realm---the realm of meaning---that is not simply a product of human thinking and thus cannot be defined by human thought.
John Micheal Greer
Inside a Magical Lodge
(a book I quite enjoy and recommend)