I have lunch with an ex-student of mine and she says something profound that occupies us for the rest of the lunch. I ask her what she is doing for the summer, and she -- who is an arts student -- says she is studying astronomy. I am surprised and amused, and say, Why? And she says, the stars change when you know something about them. Go on, I say. She says, we have a cottage up north, and I always wanted to know what the stars were, all the constellations, etc., but never got around to it. And as I am learning about them, the sky looks different, deeper, more interesting.

We exchange examples of this. I talk about how the woods look different when you know something about the ecology, and can name the different trees. She says, yes, it stops being just an undifferentiated background and springs into complex patterns. I talk about learning music and how that has completely changed the way I hear music -- it has depth and quirks and shapes -- it stopped being background. The same thing about painting -- you start seeing shadows differently, and you can grade colours better. We end lunch, and I ask her what she is going to do this fall. Oh, she says, I'm thinking of getting my pilot's licence. I say, so you can work on the daytime sky. And we smile, and part company....