I hope to add to the reservoir of resources here that Don's provided for depth of understand and personal growth. We learn much from others and can share freely today in most places.
What I'd like to present is a process developed by William Swygard in the 1950s that took me for the ride of a lifetime when I was first introduced to it in 1989. For years I looked for an audio version online that I could share with others, though it's best with an actual faciltator. I couldn't find one, so about a decade ago I created one as best I could then, using binaural beats and solfeggio tones to accentuate the journey within. I offer it as a gift with an invitation to explore: https://youtu.be/QNmXpBJJ3hk