I had a bit of a light bulb go off today. I think it captures what I like so much about data visualization.
The "Ahh" is that feeling when you begin to obtain a resolution of the thicketed nest of data and concepts interacting in your head, frustrating a comprehension you know is in there somewhere. The "Ahh" can be a satisfying unwinding of sorts.
The "Aha" is the insight you can can get once the thicket starts to become organized. The types of insight can be totally unexpected. It can be sublime.
I found two other hits with the phrase "the ahh and the aha". One use is by a yoga instructor. Another is on a Universalist blog. This makes sense. For me at least, this is all part of a comforting zen.