Sogen Hori deserves credit for giving us the most complete translation of 'Zen capping phrase' material(jakugo). Besides the Zenrinkushu (ZRKS), he has also presented material from the Zengoshu (ZGS). Some Zen temples will insist on using the latter. Hence, those wishing to undertake training with 'jakugo' will find what they need - in 'Zen Sand. '
So - why only 'four stars'? The answer, regrettably, is that the supplementary material - introductory chapters, glossary etc., seem to have been put together in haste. It looks impressive - but, something of a 'tour de force.' Too many issues are 'fudged' and hopelessly vague. A glaring example of this, is Hori's circular deliberations about the status of the 'jakugo' in the ZRKS. Despite presenting the ZRKS phrases - for use, Hori questions their relevance, suggesting that Hakuin's reforms probably rendered them redundant (p. 82). Only a few lines later, Hori admits that "it is not known what these reforms consisted of, or who was responsible for them." In the next few lines (ibid.), Hori swings back into the affirmative, telling us that - 'Rinzai monasteries everywhere' now use the the 'Hakuin-no-kenge' - or koan responses accepted by Hakuin. But - having told us that such reforms may not have been Hakuin's at all, why put the matter back in Hakuin's mouth? The chances are that the 'fixed' koan responses alluded to here were introduced by Hakuin's successors in the Inzan Ien/Takuju Kosen lines, another matter. Of this, we learn nothing. All too vague when it comes to pinning doubts on the suitability - or otherwise, of the ZRKS.
Amorphous distinctions abound. In one place (p.95) we are told that 'Rinzai capping phrase practice is . . .carried on only in Japan,' but elsewhere (p.44) Hori refers to this innovation as a return to the 'origins' of the tradition. Alas, a number of Hori's comments cast doubt upon his familiarity with the 'original' tradition. For reasons best known to himself, Hori avers (p.69 )that 'dokusan' was more or less a Japanese innovation, relatively rare in the Chinese temples. But the practice of 'ju-shih' or 'entering the master's room for special instruction' features in many Ch'an records - viz. Lin-chi, Mu chou etc. An early instance of it, can be found in the story of Hui-neng's 'secret interview' with the Fifth patriarch. Wu Cheng-en even alluded to it in his novel, Hsi-yu Chi. Besides, it was listed in the very 'rule books' (ching-kuei/shingi) brought over from China to Japan, the only difference being that - in China, it was left to the discretion of the student - when to call on the master. Chinese temple regulations made provision for it, which is even physically evident, in the ground-plans of temples brought over from China, giving prominence to the 'Fang-chang' (Jpn. hojo) or 'Abbot's room.' Despite the sinophile pretensions, Hori has a tendency to project his own preconceptions into the 'origins' of the tradition - as in a puzzling reference to the koan being developed or taking shape 'outside' the monastery, while the practices 'inside' - remained 'Indian' viz. the 'chih-k'uan' practices of Chih-yi. In fact, Chih-yi's T'ien-tai teaching was equally part of the sinification of 'Indian' Buddhism and intimately tied up with the development of Ch'an/Zen. There is little evidence to suggest that the 'koan' evolved outside Ch'an temples. It emerged from the dialogues characteristic of life in the Ch'an monasteries. What Hori probably had in mind, was the inter-action between Chinese Ch'an monks and the secular literati - in Sung China - but, that is late in the day, and putting the cart before the horse.
Again, not everyone will agree with Hori, when he suggests (p. 11) that the 'koan' is only indescribable, in the sense that the 'aroma of coffee' is indescribable. This is merely a kind of empirical truism. Surely, the 'vertical' aspect of the koan is indescribable, because the subject-object relationship - as conventionally conceived, no longer obtains. What can be described - is the 'guest' view. None of the T'ang masters ever tried to speak of the 'host' - showing their open hands - or returning to their room, to indicate the return of 'function' (guest) to the 'host' (substance). . .
The glossary suffers from kindred weaknesses. Whole pages have been devoted to dynastic founders, statesmen, generals, poets and the 'dramatis personae' of Chinese history, yet key Zen figures, idioms etc. get scant attention. For instance, Lin-chi's 'three essentials' and 'three mysteries'(sanyo/sangen) merit little more than pedestrian comments - viz. (p. 717) "in the early stages of practice, it is better to regard these as 'Zen insight' " - in short, no 'gloss' - no 'explanation' at all. Rinzai has faded into a kind of after-thought. People will value Sogen Hori's work - for the main entries. The commentary material is another matter, somewhat problematic. I wouldn't question the worth of Hori's main text-entries, or the use of jakugo as such, but without discretion, it could simply end up as a kind of 'glasperlenspiel.' For a more user-friendly approach, take a look at the 'Zen Grove Handbook' by Zenrin R. Lewis.