When we look at something we're not actually seeing the thing we're looking at. What we're actually seeing are the particles of light reflected off the thing. Those particles bounce off the thing, they hit us, and our brain interprets them as the thing itself. But all that comes in contact with us, all that we can really see, are the particles of light -- not the things themselves. Compare that to when we touch something.
When we touch something we're in actual physical contact with the thing itself. The contact is immediate - there are no "particles of touch" reflected off the thing, interpreted in the way particles of light are interpreted. That's why, I believe, that when we hug someone we get something from it that we don't get just by looking at them. Our experience of touch is directly with the thing itself. It's real.
But that's not how we see. When we look at something we don't experience it directly, we can only experience it secondhand. Sight isn't immediate, it's mediated by the gap between us and the thing, and that gap can only be closed by the light. When it's completely dark, we can't see a thing - it's like things aren't even there.
For these reasons, when I paint, I'm trying to paint the only stuff I actually see, and that's the light. I'm hoping to close the gap between me and the things in the world, between my eyes and yours, by painting the particles of light.