This is really a 3 volume set of books: a text, a workbook along with a teacher's manual, which i examine from repeatedly, and have for the past 31 years. It is probably the most important spiritual messages of our time. The Course combines 21st Century psychology with non-dualistic metaphysics. https://www.youtube.com/channel/UCXpL4OXSmktqlP6_S5p5jIQ