I want to assure you of the necessity for spiritual reading. It is a great source of mental purification when engaged in as an extension of meditation by maintaining inner awareness through japa while reading.
The yogi need not be an intellectual–perhaps even should not be. But he must be intelligent and informed–not so he can burden others with revelations of his knowledge (which must not be confused with wisdom), but so he can attune himself to the departed masters of the spiritual life who have infused their writings with their own state of realization. Also, he needs to ponder inwardly about those ideas, engaging in an intellectual version of chewing the cud. If he does not think about these high things, what will he think about?
At the beginning of my yoga search I was in a harshly anti-intellectual yoga cult that wanted the members to read nothing but its own publications which were very few and very feeble intellectually. I was always rebuked when others saw my “big” library of not even two dozen books! One leader expressed chagrin when he learned I had read the Gospel of Sri Ramakrishna. Why? Because their teachings were so minimal and inconsequential, as well as without any basis in authentic Indian texts, they were terrified that their members might encounter other, better and more sensible ideas. They were right… I did and I quit. Such a mentality is one sign of a destructive cult.
A yogi should not hesitate to look into any philosophy or spiritual inquiry. He should be very informed about the various religions and philosophies of the world.
Although I am going to recommend some books to read it is just a hint. There is a big world out there and since we are living in it we should take advantage of it. There are not only books out there, there are immense resources on the internet, including many websites which are actual libraries of online texts, including our own ocoy.org.
There are four books whose value cannot be estimated. They are foundation stones of understanding spiritual life and spiritual philosophy. They should be read through many times carefully and reflectively. I think they should be made the yogi’s lifetime companions and guides.
1) The Bhagavad Gita. There are many translations, but my favorite is: The Song of God: Bhagavad Gita, translated by Swami Prabhavananda of the Vedanta Society of Southern California. It is remarkably beautiful language, yet accurate. In many places the translation is interpretive, but according to the commentary of Shankaracharya and other authorities. I recommend you also get the translations of Swamis Swarupananda and Sivananda, and that of Winthrop Sargeant. My commentary, The Bhagavad Gita For Awakening, might be useful.
2) The Upanishads, Breath of the Eternal, by Swami Prabhavananda. The Upanishads are the basis of the Bhagavad Gita and contain thrilling expositions of the nature of the Self and its realization. My commentary, The Upanishads For Awakening, might also be useful.
3) Meditation and Spiritual Life, by Swami Yatiswarananda of the Ramakrishna Mission of India (in America: the Vedanta Society). This book is immensely practical and insightful. It covers virtually every aspect of the yogi’s spiritual life.
4) The Philosophy of Gorakhnath, Akshaya Kumar Banerjea, Motilal Banarsidass. This is a masterful exposition of the teachings of India’s greatest yogi.
These are treasures beyond evaluation. The Gita should be read daily, and it is still supplying me with new insights. I am sure it will do the same for you.
The books of Paramhansa Yogananda are extremely valuable. I especially recommend:
Man’s Eternal Quest (collection of talks).
The Divine Romance (collection of talks).
Journey to Self-realization (collection of talks).
The Science of Religion.
Sayings of Paramahansa Yogananda (originally The Master Said).
God Talks With Arjuna, (commentary on the Bhagavad Gita).
The Second Coming of Christ, (commentary on the Gospels).
I also highly recommend these books about Yogananda: The New Path and Paramhansa Yogananda; both by Swami Kriyananda. And The Life of Yogananda: The Story of the Yogi Who Became the First Modern Guru, by Philip Goldberg.
Conversations With Yogananda by Kriyananda is an absolute treasure.
In addition you need some Sanskrit dictionaries. I recommend: A Concise Dictionary of Indian Philosophy by John Grimes, The Yoga-Vedanta Dictionary of Swami Sivananda, Sanskrit Glossary of Yogic Terms by Swami Yogakanti and A Sanskrit Dictionary by John M. Denton. My own endeavor, A Brief Sanskrit Glossary, is certainly helpful, and definitely complements them.
For the authentic teachings of Christ I heartily recommend The Aquarian Gospel of Jesus the Christ, by Levi H. Dowling. This is a transcription of the psychic investigations into the life of Christ made by Dowling in what is popularly known as “the akashic records” and I believe contains the authentic teachings of Jesus, but makes no claim to infallibility or absolute accuracy.
I also urge you to get The Complete Mystical Works of Meister Eckhart translated by Maurice O’C Walshe. It is expensive but you will use it the rest of your life. Meister Eckhart: A Modern Translation by Raymond Blakney will do if your budget is limited. But do not forget the Complete Works for the future.
For the facts about diet, I recommend Diet For a New America by John Robbins, What’s Wrong With Eating Meat? by Vistara Parham, the books of Dr. Neal Barnard, particularly Food for Life: How the New Four Food Groups Can Save Your Life. The best researched and most informative books on nutrition and health are Dr. Michael Greger’s How Not To Die and How Not To Diet. For vegetarian and vegan recipes the cookbooks of Robin Robertson are very good.
Next in Living the Yoga Life: Gorakhnath Speaks To The Yogi