Read
I don't know if you know this book, but chances are you never came across this particular translation, which I think is the most beautiful one existing so far. I'm talking about the Tao Te Ching.
After seeing Swami Sarvapriyananda's lecture on the Madukya Upanishad it makes even more sense.
In a more expanded and practical form, there's Ken Wilber's book on Integral Life Practice that I really want to read again.
And in a more philosophical and comprehensive form there's also Wilber's Sex, Ecology, Spirituality that I still haven't read entirely.