Well, Kenneth Clark remarked in one of his books, that

The thing that distinguishes a landscape painter is an especially intense emotional response to light.

I do believe that's true.

There are, sounds crazy to say, but in my dark room, in Colorado,

After I've been working for days, or sometimes months outside, and if I was working in the dark room,

And I knew that it was day time, I swear I could tell, in the dark room,

When the sun came in and out from behind clouds.

Light is a physical thing that we are working with.

It's also obviously a metaphor. It's what you are working with to arrive at metaphors.

It's the age-old symbol for truth. It's the expression of truth.

Yea, it's a loaded thing, but fundamentally though,

It is just a deeply mysterious, compelling ingredient

For your understanding of life and your response to it.

I'm not sure if I can say anything more about it.

It's at the center of why one makes pictures and how one makes one.