I remember that one night we had travelled all night in a caravan, and in the morning slept on the edge of a great forest. A strange man who who had accompanied us on our journey let out a cry, and went off into the wilderness, not stopping for a moment.
When I woke up I met him again, and asked, "Where did you go?" He replied, "I heard the nightingales pouring forth their plaintive songs from the trees, and the quail uttering their cries from the mountains, the frogs from the water, and the beasts from the forest. I thought to myself: it would be ungrateful for me to slumber neglectful, while all the creatures were engaged in praising creation."

from The Gulistan of Saadi of Shiraz