Brian Weiss says there are multiple dimensions. It's not as simple as we just reincarnate in another life. There are lives which we perceive as being in the future and lives we perceive as being in the past. These lives have been recalled by various clients in his practice and that is how he knows about them.
Brian Weiss says that he is often contacted by scientists and in particular physicists who say that what he has learned from his practice synchs with string theory. Toward the end of Carl Sagan's life, BW had various conversations with him and Carl Sagan remarked that he hadn't been acting like a scientist (in regard to BW's work). His attitude then changed and he was open to the idea that we never die but that we live on in consciousness.
He talked about the various lives recalled by people in his practice. There is one life (perceived as future) where the person said the population of the earth would be great reduced. We would be living a more "back to the farm" style of life that was in harmony with nature. This will take place around the year 3000. Large portions of the earth were not habitable because they are being "restored." Brian Weiss says the avenue to that state is "open." The fact that large portions of the earth were being restored does not necessarily mean that they were destroyed by depleted uranium (think Iraq) or an atomic bomb. It could be just because the people of the earth voluntarily designate them to be that way for a time.
Throughout the show he stressed that nothing is "pre-ordained" and the path is open.
Many of his patients, upon recalling a past life, experience some type of recovery from illness. He had one patient, whom I believe he said was a prominent scientist, who had breast cancer. She was doing meditation and was, as he said, really into it. When it came time for her operation, her tumors had disappeared.
On the above story, I'm not sure I have the details correct. I'm listening to the mp3 again so if I got it wrong, I'll correct myself on another post.
Birthmarks have some significance to previous lives. They can be indicators of how the person died.
It's all about learning. We are here like we go to a school. It is hard to be here and we come here because we want to learn and improve ourselves. What we're here to learn is compassion and love. There is something to the Buddhist idea that we are all one. He said that when we wage war and kill others, we are actually killing a part of ourselves.
Oh and speaking of killing, it's all about learning. If, for example, a person were to kill another person, it would not be de riguere that this person experience being killed. If the person understands that this is wrong, that is all that matters. Thus this changes the "eye for an eye, tooth for a tooth" concept of karma.
There's more but I'm getting tired. As I listen to the mp3s again, I'll come back and post more.
Cher