1. A sudden, intuitive perception of or insight into the reality or essential meaning of something, usually initiated by some simple, homely, or commonplace occurrence or experience.
2. A sudden manifestation of the essence or meaning of something.
3. A comprehension or perception of reality by means of a sudden intuitive realization.

I experienced an epiphany, a spiritual flash that would change the way I viewed myself. – Frank Maier

I had one too, yesterday, and it felt great!