Thank you for your question!
That is a mystery. Note that we explain our experiences based on our background information.
Mr. Tolle does not mention the word “soul” but he refers to this concept as “being.” He does not talk about soul consciousness either, but he mentions many experiences which are soul consciousness.
Because we have gyan, we could see the possibility for another “new” soul to have “entered” him. However, just like it happened to Brahma Baba, it will take sometime for this realization to sink in.
He is not the “only” person that had those “all of the sudden” transformations. Many gurus, nowadays have it. “Mooji” is one of them, which I could recall. “Something happened to him” and he became “enlightened.” As far as I am concerned, their experiences of “how they got there” is of no value for me. But when I read his book and I notice that those things which he is describing has happened to me, then I care about… 🙂
Note that Mr. Tolle does not have knowledge of the world Drama; he merely explains his experience and because he has an analytical mind, he can put the “why’s” to those experiences in “western” type of language (psychology/science/history) and because he “talks his walk,” people listen to him.
I seriously doubt that many people will follow what he is talking about. The questions he is asked in his book show me that; however, when people speak with him and interact with him, they follow him.
That is the beauty of talking your walk.