Big Dreams are ones that occur several times, or ones that are so vivid that they almost seem real. Big Dreams are considered to be communication from your Guardian. These are not symbolic, but are literal.
Should you have a Big Dream that has negative connotations, e.g. an automobile accident, you should immediately enact the dream once you are awake. The dream is not symbolic, but your enacting of it is. Just go Through the notions of the incident in a simple way and get it over with.
Suggested free e-books to read:
Samael Aun Weor - Magic RunesWh Auden - Baldur Dream
Aristotle - On Dreams