I'm currently reading The Book of Tea by Okakura Kakuzo. This delightful little book was published in 1906 and talks about the history and philosophy of the beverage developing into Teaism. The book is divided into sections such as The Cup of Humanity, The Schools of Tea, Taoism and Zennism, The Tea-Room, Art Appreciation, Flowers, and Tea-Masters. Kakuzo imparts such vast knowledge, but does so in an utterly charming and witty way. He had me laughing out loud several times already.
Okakura (his surname) discusses tea as an art form and a religion. What's interesting to note is that he wrote this book in English for a Western audience. If you're at all interested in tea, culture, and philosophy this is a book that should not be missed!