It’s commonly said, in the nondual teaching, that peace is what I am. Then why does it seem as if it comes and goes?

In the question is contained your stand or central presumption: namely, that I am a finite mind for which peace comes and goes.

From your stand as the finite mind, you experience objective experiences coming and going: sights, sounds, tastes, textures, and smells; bodily sensations; and thoughts and feelings.

To take this stand just is to superimpose limitations–or forms–on all experiences. Accordingly, so long as you stand as the finite mind, just so long will it seem to you, the finite mind, as if peace is like any other object in the sense that it comes and goes. (If you keep looking through orange glasses, how can you not see an orangely-colored world?)

For this reason, you must “go back” and examine the presumption: am I the finite mind?

Begin with the realization that you’re that to which all experiences are appearing. Since that’s so, how can you be the mind?

To make this point stick, look more closely. When you stay only with your own experience of your own being, do you discover that it’s thinkable? No. That it’s capable of being felt (as an emotions is)? No. Then it can’t be subject to the limitations imposed by the finite mind.

Go one step further. Staying only with your experience of your own being, do you find that it can be disturbed or perturbed in any way? No.

This imperturbability, the inability to be disturbed, is what we call “abiding peace.”

Taking your stand as awareness, you recognize, immediately, that you’re abiding peace. All that remains is to gradually stabilize in and as awareness. Then will it be very clear to you that peace is what you are, that peace is all there is.