““A common example from physics is of a pencil balanced on its point. It is symmetric, in that while it is balanced on its point, one direction is as good as another. But it is unstable. When the pencil falls, as it inevitably must, it will fall randomly, in one direction or another, breaking the symmetry. Once it has fallen, it is stable, but it no longer manifests the symmetry- although the symmetry is still there in the underlying laws. The laws describe only the space of what possibly may happen, the actual world governed by those laws involves a choice of one realization from many possibilities.””
