It's simply a way of recording what you see -- point the camera at it, and press a button. How hard is that? And what's more, in this digital age, its free -- doesn't even cost you the price of film. It's so simple and basic, it's ridiculous.
It's so difficult because it's everywhere, every place, all the time, even right now. It's the view of this pen in my hand as I write this, it's an image of your hands holding this book, Drift your consciousness up and out of this text and see: it's right there, across the room -- there... and there. Then it's gone. You didn't photograph it, because you didn't think it was worth it. And now it's too late, that moment has evaporated.