Watch a clock’s pendulum. Right, then left, then right again. It never rests at one end.

The tradition sees the same law in us. Praise lifts you and criticism drops you. A good day turns into a bad one. You love a person and then resent them. Opinions swing too: one year you believe something passionately, and a few years later its opposite.

Living at the ends of the swing is exhausting. Every high is followed by a low, because the same force carries you both ways. The more you cling to one side, the harder you are thrown to the other.

But a pendulum has a center. Its swing hangs from a point that does not move. In you, that point is the part that can watch the swing without being carried by it. It is still there when you are praised and when you are blamed.

This does not mean feeling nothing. It means feeling everything and staying yourself. You can be happy without needing the happiness to last, and sad without believing the sadness is forever.

Each practice in this book brings you closer to that center. The door question is a step toward it. So is watching yourself, which comes next.