Allan Kardec. The book of spirits (№ 396011)

Question: How do wandering spirits trained? They do this, presumably, is not the way we are?
Answer: They are studying the past and searching for funds to rise. They are looking to see what is happening in the places that they visit; they listen to the speech of the enlightened people and judgment of spirits more advanced than they are, and all this leads them to thoughts, which they did not have before.