When you ride in a boat and watch the shore, you might assume that the shore is moving. But when you keep your eyes closely on the boat, you can see that the boat moves. Similarly, if you examine myriad things with a confused body and mind you might suppose that your mind and nature are permanent. When you practice intimately and return to where you are, it will be clear that nothing at all has unchanging self.
This part is a quite straightforward account of the relationship between delusion of self and the reality expressed by the Buddhist concepts of Anatta, Sunyata and Annica.
Although there are only ever impermanent phenomena arising and passing, without any constant component, the delusions of our subjective perspective give us the illusion that we have an absolute, continuous existence through time. Just as when you are onboard a boat it may appear that the boat is stationary, and everything else is moving, so it appears that the self is stationary or continuous while the phenomena it perceives are changing. But in fact, the boat is moving and the mind is constantly changing. The is the principle of Anatta (no-fixed-self) taught in Buddhism from earliest times.
The same principle applies to all entities - sentient and non-sentient - even though our minds attribute them continuous identity or existence, observed carefully, it can be seen that nothing at all has a continuous, separate existence. In this respect there are really no 'things' except as provisional ideas of identity and continuity. This is the principle of Sunyata (emptiness of self).
Because nothing has any constant part, or fixed identity, there is nothing to obstruct reality from changing. There is nothing that is not always changing. This is the principle of Annica (impermanence).
Buddhist practice allows us to see this original reality of change and inseparability clearly, and to bring ourselves into harmony with it, being free of deluded notions of continuous self.