We have to begin answering what the purpose of reincarnation is; for starting, everything that Hashem does has a purpose, so the final goal is that every individual and anything in the world  gets to its final tikun. The same is with reincarnation, if the person did not complete the tikun in the current life he or she has to come back and try to fix it, it is important to note that one soul can reincarnate several times until it completes its final tikun.

If you are thinking that since there are going to be more chances, in concept, to do the right thing through several reincarnations and decide not to work towards completing your tikun; well, Hashem gives many opportunities for us to achieve the final goal but if the soul already went through many opportunities and instead of fixing it is doing more wrong, that’s it! Hashem burns the soul. Wait, what does it means that Hashem burns the soul? It is not that He disappears from existence that soul, but that He disintegrates that soul into many pieces and scatters those pieces into the souls of righteous people for it to accomplish its tikun.

The main principle of reincarnation is a chesed from Hashem for us to have more chances to complete our tikun. Now, getting into the topic of knowing what we were in past lives, we have righteous people that are and also those who were able to say who people were in a past life. For example, in the writings from the Arizal, specifically “Shaar Hagilgulim” (the gates of reincarnation), in the introduction...