The emptiness of self, I said, was not a difficult concept to grasp. But there's a big difference between understanding it conceptually and understanding it experientially, and understanding it experientially is what's transformative.
Which is why disciplined meditation is fundamental. Clinging to self is such an ingrained habit that loosening it requires an equally habitual experience of its insubstantiality. Sure, you hear of those people who get one kick in the head and go straight to enlightenment -- but if you look at those stories you'll see that they're usually about people who have spent a lot of their lives in disciplined meditation.
Somebody -- was it Kalu Rinpoche? -- once remarked that expecting a little haphazard meditation practice to loosen our clinging to self was like expecting to be able to free ourselves of wanting tobacco by practicing not smoking for fifteen or twenty minutes at a time, a couple times a week.