What is the theme in The Book of Tea by Kakuzo Okakura?

Teaism is a central theme in this book. Author Okakura makes it abundantly clear that the basic concepts of Teaism and the tea ceremony come from the older philosophies of both Taoism and Zennism. The first and most obvious connection is the legends handed down from generation to generation. The first tea ceremony is said to have involved Lao Tzu, the founder of Taoism. Additionally, monks in Zen monasteries are known to have involved tea in their religious rituals, offering the drink to statues of their gods.