"There you are, standing at a window watching oak leaves flutter down from dark boughs, and without warning your whole body fills with a longing for something you can't name, something you've lost but never had, that you're nostalgic for yet don't remember. You sense a joy so huge it breaks you, a sorrow so deep it cleanses."
It's from Mark Buchanan's five-star book Things Unseen -- the title of which refers to one of my favorite passages in the Bible:
"Therefore we do not lose heart. Even though our outward man is perishing, yet the inward man is being renewed day by day. For our light afflication, which is but for a moment, is working for us a far more exceeding and eternal weight of glory, while we do not look at the things which are seen, but at the things which are not seen. For the things which are seen are temporary, but the things which are not seen are eternal." (2 Corinthians 4:16-18)