Dreaming about money often has little to do with actual finances and much more to do with self-worth -- how secure, valued, or powerful you feel in your own life right now. Finding money can point to a sense of newfound worth, while losing it often reflects anxiety about your standing or a feeling of power slipping away.
Mercury can be used for one thing and its contrary because it is of a variable nature. - Picatrix (Andalusia, ~1000.AD)