Nothing exists without the presence of its opposite. When some things are seen as beautiful, ugliness appears. When some things are seen as good, other things become bad. Being and non-being co-create each other. Difficult and easy compliment each other. Long and short define each other. High and low depend on each other. Voices, instruments, and sounds harmonize with one another. Before and after follow each other. YIN and YANG balance each other. Front and back contain each other. Therefore act without doing; teach without talking; let things come as they arise, go when they depart; possess nothing; desire nothing; act without expectation; do not lust for results; let go when the work is done. The TAO is simultaneously changing and unchanging.