Most important books I have read on my spiritual journey are not by anyone writing to lecture or sell self-improvement books. Hermann Hesse, who won a Nobel Prize for Literature, is my favorite author. While my favorite is Narcissus and Goldmund (don't let the former name of the pair of friends fool you), two very short books he wrote are so full of spiritual wisdom not spoken in the voice of a teacher, just setting examples by telling stories, that they should be read before anyone decides to spend money on courses--they would be Demian and Siddhartha. I also loved Journey to the East, which is even shorter and captures the trials and tribulations of a spiritual journey to self in a nutshell. The subtitle to one edition of Siddhartha is "Your soul is your whole world." Here are two poems I wrote based on that quote and in response to 2 of Diana's poetry prompts earlier this year: https://medium.com/know-thyself-heal-thyself/your-soul-is-the-whole-world-7a149c7602ad