This is NOT an easy read by any stretch of the imagination! However, it is a tremendously important book, and it is absolutely insane that it has been allowed to go out of print! Chin Ul was one of -- and arguably the most -- important figures in Korean Seon Buddhism, and here scholar Robert Buswell has collected all his writings.
I've many issues with the Zen traditions: most notably their all-too-often tendency to sway into the reification of 'mind' in a way that sounds way too much like the Vedantic Brahman. Also, the sectarianism and obsessive harping on "lineage" and which school is the best blah blah blah. Chin Up attempted a syncretic, integrated approach which I appreciate. But still, I wish a Cao-dong (Soto) lineage or at least practice tradition had made it to Korea!