When some people learn that Buddhism teaches rebirth and also that there is no self (anattà), they find it difficult to understand how rebirth can take place. `If there is no self or soul' they ask, `what passes from one life to the next?' This problem is more apparent than real. The Buddha did not teach that there is no self as such Ý he taught that there is no permanent, unchanging, metaphysical self. In Buddhism, as in contemporary psychology, the self is understood to be a constantly evolving cluster of impressions, memories, traits and dispositions. It is this `self' that continues in the next life. It might be compared to three billiard balls in a line, each touching the other and a fourth billiard ball some distance from the three and aligned to them. If a player hits the fourth ball with his cue it will speed across the table and hit the first ball in the line. The moving ball will come to an immediate halt, the first and second balls will remain stationary while the third ball, the last in the row, will speed across the table and into the pocket. What has happened? The energy in the fourth ball has passed through the first and second balls in the row, into the third ball, activating it so that it moves across the table.
In a similar way, the mental energy that makes up what we can conveniently call the `self' moves from one body to another. Indeed, the very thing that allows this energy to pass through a medium and animate another object is its changeability (anicca). It is not this, but the idea that a soul or spirit can go from one location or dimension to another without changing that is difficult to explain.