Allan Kardec. The book of spirits (№ 396483)

Question: Two people, each other friends if they visit each other during sleep?
Answer: Yes, and many others who believe like they're strangers, meet each other and talk. You can have, although you do not suspect, friends in another country and part of the world. The fact that during sleep you meet with friends, family, acquaintances, people who might be useful or interesting, so commonplace that you do this almost every night.
Question: What would be the usefulness of these night visits if we forget them?
Answer: By awakening of them usually remains intuitive knowledge, and this often is the source of some of the ideas that come suddenly and the origin, which you think, but what is the essence of those that were drawn by you in these night.