For me it was Yoga of Herbs by David Frawley and Vasant Lad who run the Vedic Institute of North America, whereby Lad was perhaps the first major influencer of Indian herbal medicine in the western world. I had no idea that there would be seeds of cosmological and psychospiritual wisdom in a book that is widely sold as something to simply cure what ails you with dietary alchemy. So deep, really, that it made me pursue their practitioner course on my time, in an autodidactic way. And then some. I read some Bhagavad Gita. Some of the Upanishads. Nearly all of the Rig Veda. The Mahabarata. And more. And I can say that I lean strongly towards a sort of Advaita Vedanta now (non dualistic philosophy) that has very much changed my outlook on life and given me so much reason to find peace in the darkest places and be strong despite the seeming meaninglessness of life, and to not fear death, and to have far more compassion and strive for real empathy in all circumstances. It's like that. Anyway, are there books that have done this to you? I've heard of only a few that are technically non-religious.
by kairologic