He seems to mention that his wife paints. So does mine, and she understands the idea of flow because it happens when painting. Or writing. Or playing the violin. Or designing.

In fact, flow happens in loads of places, and isn't unique to geeks or programming.

To the author: get a life, and learn other stuff. Flow is common, even if not always understood or appreciated.

Why does the author think flow is a hard concept to grasp or something restricted to geeks? Basic rule of getting people to understand you: Don't assume they're too stupid to do so.