Art is challenging and frustrating but I don't linger in it. I work on five paintings at a time so if I'm frustrated I put one down and begin another.

Children don't play outside enough. For hundreds of thousands of years young people spent time outside - until 15 years ago.

My art collection is dominated by tribal art from Nigeria where I taught school, from New Guinea where we've travelled, and by Canadian Haida pieces. My own art is either on exhibition or owned by other people!

You begin paying more attention to what you're seeing when you know the names... If you don't know the names of plant and animal species that share your neighbourhood, you don't care about them and can't protect biodiversity.

I can't conceive of anything being more varied and rich and handsome than the planet Earth. And its crowning beauty is the natural world. I want to soak it up, to understand it as well as I can, and to absorb it. And then I'd like to put it together and express it in my paintings. This is the way I want to dedicate my work.

If you find yourself worrying, go outside, take three breaths, address a tree and quietly say, 'Thank you.' If you can't find a tree, a dandelion will do... Nature is magic.

I've never thought sitting around worrying helps anything, except to help shorten your life.

If I ever have a conflict between art and nature, I let art win.

Nature is not a free lunch, but we treat it as a free lunch.

It doesn't take more skill to paint hundreds of strokes rather than one right stroke but it takes more patience.

Blackwater USA has already taken in more than $1 billion from the public coffers. All in all, that's not a bad take for Erik Prince, the founder of Blackwater and a Naval Academy dropout who served less time under the colors of the nation, in uniform, than my most recent pair of boots.

The most important question facing the planet is: Is it worth it?

Aesthetic pleasure is not to be taken lightly it's very important for the spirit and therefore the health.

In art and science we are now in a delta, at the end of the long flow of progress. In a delta there is no clear direction but there may be many choices. The best we can do is to enjoy the choices that we have and to be genuinely and creatively eclectic.

To me the most important thing in a piece of art is the thought. Technique is totally secondary.

After being an Impressionist, Cubist, and an Abstract Expressionist, I was influenced by realistic artists, including Andrew Wyeth in the late '50s, and I haven't changed my style since.