As you can see, my reading orientation is towards the study of depth meaning and human transformation. This page lists more the authors than the one book per author - any of these authors' books are recommended. If you take your reading seriously, I would not recommend studying such books in the absence of a mentor or reading group as they can cause a great deal of disorientation.
Abraham Maslow. Religions, Values, and Peak-Experiences. Difficulty: 7.5-8 /10
Aldous Huxley. Doors of Perception: Heaven and Hell. Difficulty: 6.5/10
Barbara Miller (Translator). The Bhagavad Gita. Difficulty: 7/10
Carl Honore. In Praise of Slowness. Difficulty: 5/10
Carl Jung. Man and His Symbols. Difficulty: 7/10
Carl Rogers, Jerome Freiberg. Freedom to Learn. Difficulty: 5/10
Christian Smith, Melissa Denton. Soul Searching. Difficulty: 6.5-7/10
Coleman Barks (Translator). The Essential Rumi. Difficulty: 6-9/10
Daisetsu Suzuki, Erich Fromm, Richard De Martin. Zen Buddhism and Psychoanalysis. Difficulty: 7.5/10
Daniel Gilbert. Stumbling on Happiness. Difficulty: 5/10
Daniel Goleman. Emotional Intelligence. Difficulty: 5/10
Daniel Harbour. An Intelligent Person’s Guide to Atheism. Difficulty: 7/10
David West. Reason and Sexuality in Western Thought. Difficulty: 8/10
Derren Brown. See clips on uTube. Difficulty: easy
Dogen Zenji. Primer of Soto Zen. Difficulty: 8/10
Eric Fromm. The Art of Loving. Difficulty: 6.5-7/10
Ernst Schumacher. Small is Beautiful: Economics as if People Mattered. Difficulty 6-7/10
Evelyn Underhill. Mysticism. Difficulty 7-8/10
Fiona Terry. Condemned to Repeat. Difficulty: 6/10
George Orwell. 1984. Difficulty: 6/10
Harry Triandis. Individualism and Collectivism. Difficulty: 7/10
Herbert Spencer. The Conditions Essential to Human Happiness. Difficulty: 8/10
Hubert Dreyfus. What Computers Still Can’t Do. Difficulty 7-8/10
Ivan Illich. Deschooling Society. Difficulty: 9/10
James Garbarino. Lost Boys. Difficulty 6.5/10
Jean Jacques Rousseau. On Education. Difficulty: 7-8/10
Jill Taylor. Stroke of Insight. Difficulty: 5-6/10
John Ruskin. On Art and Life. Difficulty: 7-8/10
Joseph Campbell. Myths to Live By. 8-9/10
Karen Armstrong. The Case for God. Difficulty: 7-8/10
Leo Thomas. The Healing Team. Difficulty: 6/10
Lewis Mumford. Technology and Civilization. Difficulty: 7-8/10
Michael Pollan. The Omnivore’s Dilemma. Difficulty: 6/10
Neil Postman. Amusing Ourselves to Death. Difficulty: 7/10
Paul Tillich. Dynamics of Faith. Difficulty: 8-9/10
Peter Singer. Writings on an Ethical Life. Difficulty: 6-7/10
Philip Kapleau. The Three Pillars of Zen. Difficulty: 7/10
Robert Aziz. The Syndetic Pardigm. Difficulty: 8-9/10
Thich Nhat Hanh. The Heart of the Buddha’s Teaching. Difficulty: 6-7/10
Reinhold Niebuhr. Moral Man and Immoral Society. Difficulty: 10/10
Samuel Bercholz, Sherab Chodzin Kohn. Entering the Stream. Difficulty: 7/10
Thomas Cleary (Translator). The Taoist Classics, Volumes 1-4. Difficulty: 8/10
Thomas Green. When the Well Runs Dry. Difficulty: 7/10