When Zen Buddhism crossed from China to Japan in the twelfth century, it entered a phase of development that was not only to inspire a magnificent range of artistic achievement but also to exert a tremendous influence upon Japanese life itself and, eventually, to bring to the attention of the West a religious philosophy both unique and challenging in its power. 'Yet,' as one of the contributors to A First Zen Reader expresses it, 'If asked what Zen is, to reply is very difficult.' It is the purpose of this anthology to suggest an approach to such a reply.