The pendulum of the Dao swings back and forth between decay and renewal. All that has risen will fall, all that has fallen will rise again. Structures collapse, trees fall, mountains crumble, but all shall renew. Man grows old but few learn. The tides are high and then low, the oceans rush to the shore and then back again. All these cues from nature should be enough to teach us something, but most people are unwilling to learn. If we just had enough time, could somehow hold it like clay in our hands and stretch it, perhaps we would know. Time is the greatest teacher, but ultimately kills all its students.