Although "The Joyful Wisdom" may be considered in the light of an interpolation into Nietzsche's philosophical works, the book is nevertheless among the most interesting of his output--not so much because it gives us any additions to the sum of his thinking, but because it throws a light on the philosopher himself. It may be lifted bodily out of his works without leaving a gap in the development of his doctrines, but it cannot be set aside without closing up a very important and significant facet in the man's nature. Unfortunately Nietzsche is looked upon as a man who was entirely consumed with rancour and hatred--a man unconscious of the comic side of existence--a thinker with whom pessimism was chronic. But this is only a half truth, a conclusion founded on partial evidence. Nietzsche's very earnestness at times defeated his own ends. "The Joyful Wisdom" is one of the most fundamentally hilarious books ever written. It deals with life as a supreme bit of humour. Yet there is little in it to provoke laughter. Nietzsche's humour is deeper than the externals. One finds no superficial jesting here, no smartness, no transient buffoonery. The book is a glorification of that subtle joy which accompanies the experiencing of knowledge. In order to catch its spirit it is necessary that one be familiar with the serious and formulating Nietzsche, for on his most serious doctrines is founded that attitude which makes "The Joyful Wisdom" hilarious. Once familiar with Nietzsche's earlier writings one may read the present book with a feeling of exhilaration unlike that produced by his more manifestly solemn writings.