“What is Zen?” This is one of the most difficult questions to answer, I mean, to the satisfaction of the inquirer; for Zen refuses even tentatively to be defined or described in any manner. The best way to understand it will be of course to study and practise it at least some years in the Meditation Hall. Therefore, even after the reader has carefully gone over this Essay, he will still be at sea as to the real signification of Zen. It is, in fact, in the very nature of Zen that it evades all definition and explanation, that is to say, Zen cannot be converted into ideas, it can never be described in logical terms. For this reason, the Zen masters declare that it is “independent of letter,” being “a special transmission outside the orthodox teachings.” But the purpose of this Essay is not just to demonstrate that Zen is an unintelligible thing and that there is no use of attempting to discourse about it. My object, on the contrary, will be to make it clear to the fullest extent of my ability, however imperfect and inadequate that may be. And there are several ways to do this. Zen may be treated psychologically, ontologically, or epistemologically, or historically as I did in the first part of this book to a certain extent. These are all extremely interesting each in its way, but they are a great undertaking requiring years of preparation. What here I propose to do, therefore, will be a practical exposition of the subject-matter by giving some aspects of the _modus operandi_ of Zen instruction as carried out by the masters for the enlightenment of the pupils. The perusal of these accounts will help us to get into the spirit of Zen to the limits of its intelligibility. I