The Zen Commentary on the Lankavatara Sutra by Kokan Shiren (1278-1346) and its chief antecedent, the commentary by the Khotanese monk Zhiyan

Zen scholarship, especially on the sutras and sastras, has been largely neglected for ideological and aesthetic reasons. The Zen slogan of "non-dependence on letters" and "direct pointing at the mind' supposedly left little room for scholarship and yet Zen has the most extensive literature of any East Asian Buddhist school or sect. However, most of this literature is of the goroku (logia) type, the sayings and formal, ritualistic texts, combined with collections of poetry of selected Zen monks. Related and derived from these are the koan (Ch. gong'an) collections of paradoxical dialogues and questions. The other major genre is the "transmission of the lamplight" genealogical histories that string together Zen masters in a lineage with skeleton hagiographies and incidents of enlightenment, often to become the subjects of koan. Translators and students of Zen have preferred this literature for aesthetic and ideological reasons, being often besotted with the humour, outlandish images and the romantic aura of the eccentric master, or with the beauty of the poetry; itself often not fully understood.