Trying to discover what we really are is the practice of understanding “no-self.” Insisting that there is a self means we cannot let go of attachments — the self is a big attachment!
There also seems to be something that is frequently called “the watcher,” that which seems to be observing all this, and perhaps this is really the “I” in question. Strangely, the watcher cannot be found, can it? It seems to sometimes be our eyes, but sometimes not, sometimes it seems to be images in our head and sometimes something that is separate from them and yet watching the images in our head. Sometimes it seems to be our body, but sometimes it seems to be watching our body. Isn’t it strange how we are so used to this constant redefinition of ourselves that we never stop to question it? Question it! This odd sense of an unfindable watcher to which all of this is happening yet which is seemingly separate from all that is happening, which sometimes seems in control of “us” and yet which sometimes seems at the mercy of reality: what is it really? What is going on here?
One of my teachers once wisely said, “If you are observing it, then it isn’t you by definition!” Notice that the whole of reality seems to be observed. (Source: Mastering the Core Teachings of the Buddha, by Daniel Ingram)
No-self is closely related to emptiness. If all things have no self-nature, then they are empty. Everything is always changing, so it follows that they have no essence, no fundamental permanence. I begin to see that impermanence and emptiness and no-self are like one, or aspects of one another.