The book opens by tracing how tea passed from medicine to beverage to a religion of aestheticism the author calls Teaism. He presents it as a cult founded on the adoration of the beautiful among the sordid facts of everyday existence, a worship of the Imperfect that quietly inculcates purity, harmony, and a sense of proportion to the universe. Teaism, he argues, has shaped Japanese homes, habits, and art alike.
Okakura frames the work as a plea for understanding between East and West. He laments that the West admires Japan for its capacity for war yet ignores the gentler Art of Life embodied in tea, and protests against the curious web of facts and fancies woven about Asia. Humanity, he observes, has so far met only in the tea-cup, the one Asiatic ceremonial that commands universal esteem.
Tracing the history of tea through its Boiled, Whipped, and Steeped schools, he treats each manner of preparation as a portrait of the spirit of its age. He then turns to Taoism and Zennism, the philosophies from which Teaism springs. Taoism, the art of being in the world, locates reality in the present and prizes the Vacuum; the art of life lies in a constant readjustment to our surroundings.
Zennism, he explains, makes these Taoist ideals practical by recognising the mundane as of equal importance with the spiritual, so that greatness may be found in the smallest incidents of life. From this grows the tea-room, a deliberately plain and ephemeral cottage whose austere simplicity, purity, and reverence for emptiness embody the same conviction that suggestion and reticence matter more than ornament.
The closing chapters apply this vision to art appreciation, flowers, and the tea-masters themselves. True appreciation, he holds, is a sympathetic communion between work and beholder, and a masterpiece must leave something unsaid for the viewer to complete. The tea-masters, who shaped Japanese taste in painting, gardens, and conduct, lived their philosophy to the end, treating life and even death as a final work of art.