in Thoreau’s Journal:

Walking in the woods, it may be some afternoon, the shadow of the wings of a thought flits across the landscape of my mind, and I am reminded how little eventful are our lives. What have been all these wars and rumors of wars, and modern discoveries and improvements, so called? A mere irritation in the skin. But this shadow which is so soon past, and whose substance is not detected, suggests that there are events of importance whose interval is to us a true historic period.