Poetry, unwritten

Have you ever felt that need, that urge to write, without even being sure what should you write? The feeling that you really must shape something in words, an unnameable feeling, elusive, trying to find its way from the out-there where it comes from, and trough your very own head.
But then, that feeling evaporates, and leaves only a misty trace, fading quickly from the blank paper of history. A single colour, a tune, a poetry line.
What is it, that feeling? Where does it come from?  
I don't know what it is, and I feel unable to grasp it, to give it a form. It is in the sunlight, which filters through the leaves of the trees and falls on my face as I lay on the grass. So I just roll and take a picture of it. A hopeless effort to catch the eternal sunshine of a silent moment.