Valuable lesson taught by Dao is aging. No one has figured out how to stop aging. Trees rise from saplings to towering high. Then day comes when they topple over. It is most wise to age gracefully and wisely. Most interesting how as young offspring, we seek to grow older to satisfy dreams. Yet when older, we often look back longingly, desperately seeking to remain young somehow. Old saying; 'there is no fool like an old fool', but fools come in many ages. A person who is comfortable with aging process demonstrates great wisdom.