Among the modern martial arts most often mentioned in relation to "spirituality" is the Japanese martial art aikido, created by Morihei Ueshiba (1883 -1969) in the 1940s. He described aikido as an art of peace and viewed its practice as a spiritual endeavour. Academic observers, however, have cast doubt on the authenticity of spiritual content in the martial arts while others consider that spirituality is not possible outside the confines of established religion. This book refutes these arguments by exploring in detail aikido's relationship to Japan's spiritual traditions. Drawing extensively on Ueshiba's discourses and writings, it compares the aikido world view and practice methods with those of four belief systems influential in Japan - Daoism, Zen Buddhism, Shingon Mikkyo and Shinto. The book shows how Ueshiba pierced the meaning of these traditions and was able thereby to synthesise their spiritual practices creatively. It also sheds light on various sources of confusion surrounding spiritual aspects of the martial arts and should interest martial arts' practitioners and anyone concerned more widely with new forms of spirituality.