"Photograph what you can't see."
I know. It took me a while to understand what Michael meant. And I think, I think, this is in the spirit of being an observer rather than a creator, which was how Michael described the art of photography. It reminds me of the late Malaysian filmmaker, Yasmin Ahmad, who was also an icon in the world of advertising. Just like Michael, Yasmin was a fan of the Japanese philosophy. When asked about how she got her ideas, she said that when you put your ego first, that's about as big as your idea could go. When you take a step back and let God (or nature, or whatever supernatural being you believe in) reveal things, the idea could be as big as the world. Especially in the case of long-exposure photography, it's about having the patience and letting your camera take its time absorbing the beauty that's not immediately visible to your naked eye.
Anyway, a picture says a thousand words, and I think this amazing shot by Michael probably explains the lesson better, so here you go:
(Picture taken from Michael's online gallery here)