The best practical advice to beginners, and even to many who think they are proficients, is a warning. However solemn the message seems to be, however inspired the accompanying state of mind apparently is, do not automatically and unquestioningly believe that the Lord is speaking to them. If they object that surely at such a time as sacred prayer or uplifting meditation the Lord would not let them be deceived by evil forces, the answer is that the question is wrongly put. It is they, and not necessarily the evil forces, who deceive themselves.
-- Notebooks Category 16: The Sensitives > Chapter 14: The Sensitive Mind > # 98