Reincarnation is, by far, the most frequent occurrence, which is why it deserves special attention. The pioneering work of Ian Stevenson and recently of other researchers can provide some fairly credible empirical evidence (as far as it can go) in this respect. From the Synthesis perspective, it makes sense that every soul goes through a series of lives. Reincarnation enables development of awareness and intent through experiences in the material world (although, of course, these experiences could also have negative effects). Thus, every physical life is an opportunity to increase awareness and control and to improve the ‘shape' of the soul (so it is unlikely that a human soul would connect to an animal body, for example). The soul can stop reincarnating when a heavy and slow body is not necessary any more to keep it together - in other words, when a crude moulding is finished. Until the shape is optimal, until the self is able to maintain, expand and control energy without the help of the body, the soul goes from one life to another. When the first ring breaks apart, the other rings can maintain the energy coherent and separated from other souls, but only temporarily. Sooner or later, they break apart too, and the soul is, in most cases, again attracted by matter.
Previous lives are hard to remember because there is no connection - the associative chain is discontinued. As when we dream, not only do we not remember the awake state, but we usually don't remember previous dreams either. We are attached to the experience of the dream we are in, so if there is no link, there is no propensity to remember. How can one remember previous dreams, if s/he does not even know that s/he is dreaming? Even more importantly, those memories have lost their form and coherence (because the rings have broken down). Overall, this is an advantage, the previous memories could be confusing and not conducive to development (if you played draughts, and now you are learning how to play chess, better to forget draughts). Sometimes, however, especially in the cases of a sudden death and a rapid return, the rings do not dissolve completely, some ‘pieces' may be still left attached to the soul after it connects to another body - which is why some people can recall a few fragments of their previous lives (but this is likely to be a less frequent occurrence than reported in popular literature). Snippets of memories can also be reconstructed by corresponding energy configurations and are normally accessed outside the present context (e.g. in sleep). Moreover, they are influenced by current experiences, so their interpretations may not be always correct.