Definitely read anything by Ram Dass, but especially Be Here Now. It will blow your mind..

Ram Dass is a yogi formerly known as Richard Alpert, a psychologist who worked with Timothy Leary. They got fired together after doing LSD research with grad students at Harvard. Be Here Now is a groovy psychedelic and artistic rendering of his experiences in India after Harvard, where he went to look for answers to the questions about spirituality he was encountering through drug experience.

It's the kind of book that speaks to the secret truth hidden in everybody. The author seems culturally Hindu/Buddhist at first glance, but he was born Jewish and considers himself a practitioner of all faiths.

Please don't read books by people who claim to have the only path to truth. The teachings of the mystics tell us that even distinctions between God and no-God are false... Reality is One and we all share it.