Epiphanies are functionally similar to orgasms in that both are emotional "rewards" for "connecting."
In the case of orgasm, the connection is sexual. While in the case of epiphany, the connection is conceptual. That is, my epiphanies occur when I connect concepts. Heidegger would note that both forms of connection share the same Latin root: copula葉o link. <grin>
Of course, not every conceptual connection triggers an epiphany. Dave Winer says he has them when he has an idea that mixes well with the world. My epiphanies are triggered when I make a broad set of connections between concepts that had seemed unconnected and such connections lead to a whole series of insights.
Why do both ways of connecting (sexual and conceptual) trigger an emotional feeling of pleasure and satisfaction? I believe it is because both forms of connecting are essential to evolution, i.e., genetic and memetic.
BTW, I disagree with Dave's apparent suggestion that mostly women understand this relationship between sexual and conceptual connection. Google epiphany orgasm and you'll find many men observing the connection between them. When I did so, I found at least one man who has apparently thought about this extensively: Neil Greenberg, Professor of Ecology and Evolutionary Biology in the College of Arts and Sciences, University of Tennessee, Knoxville. His web site has interesting pages on epiphany as a state of consciousness triggered by connecting. Here's one other man who's made the connection.
My four greatest epiphanies (roughly spaced by decades) were triggered by the following (in order):
ｷ The realization of finality of death and my embrace of atheism
ｷ The realization of the fundamental importance of conceptual connection in the evolution of complexity
I hesitated to post this because it sounds so wacko, but given how many others have commented on the phenomenon, I felt I had to add my perspective on the issue.