343. When a person has invoked his relations and friends, some celebrated personages, to compare their opinions as spirits with those they had during their lives, he is often embarrassed to sustain a conversation without falling into trivialities. Many persons think that the Book on Spirits has exhausted the series o questions on morals and philosophy : this is an error ; for this reason it may be useful to indicate the source whence almost illimitable subjects for study may be drawn.
