This is definitely a three quantity set of textbooks: a text, a workbook and a teacher's manual, that I read through from repeatedly, and possess with the earlier 31 years. It is amongst 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