I bought this book long ago and Amazon's systems keep pestering me to review it, although I haven't read it properly. I had previously bought the "Blue Cliff Record", and unless you can devote your whole day to koan study, that by itself will see you out of this world. Buying this as well was like the man who wins a lifetime's supply of free beer and is so excited he goes out and buys a second lifetime's supply.
But who can resist endless computer nagging? Besides, the reviewer below, who seemed to like the book in so far as you can tell, yet only gave it one star, has skewed the ratings. (He gets "wandering in samara" confused with "Appointment in Samsara", so maybe he was just ignoring the Precept about Not Using Intoxicants.)
These hundred "cases" were collected by Master Hung-chih; the prose commentaries were added by Master Wan-sung Hsing-hsiu, playing the role that Master Yüan-wu did in the "Blue Cliff Record". Thomas Cleary's Introduction is a useful brief history of Zen. "Serenity" isn't quite the word: "The Book of Equanimity" says it exactly. Equanimity is a deep perception of Oneness, or of the Indescribable beyond even Oneness: if you realise it with heart, soul and body, you know that water can't drown you, that fire can't burn you.
So what is a Koan? An IQ puzzle? A logical enigma that enables you to see the limits of rational thought? A mysterious aphorism that you should just Be With, not try to solve? Heck no! A Koan Is A Plain, Clear Statement About Something You Are Quite Capable Of Understanding. Laughter is the usual response when you see into a koan ("solve" is misleading.) I'm not entirely sure what's so funny. Partly it's that it was all so obvious: something insanely wonderful was right there in front of you all the time.
Koan-study is easy. All you have to do is give up all interest in everything else, abandon all plans for the future and throw away your body and life itself. No-one can help you: you have to see for yourself. Pick a koan from the "Mumonkan", the "beginners" koan collection, pick one that intrigues and puzzles you.
Do you feel utterly, hopelessly baffled? You can't figure out even how to begin thinking about it? You can't see how anyone could solve it, how there could possibly be a solution? When you try to think about it, you feel as if your head has been wrapped in several layers of cling-film? Great! You're on the right track already. Pretend that somebody inside you understands perfectly. If you try to think it out for yourself, he or she will fold his or her arms and say, "Fine, you can do without me." But if you feel thoroughly baffled, so lost in bafflement that you can hardly recognise your own name or words like "soap-dish" or "pillow-case", he or she will say, "Oh, you need my help. Sure. Watch this."