‘“Turning words” are expressions that turn one to realization’ (Aitken 1991, 24) – whether spoken with that intention or not. Somehow they overcome the inertia that keeps you moving in the same habitual direction. But is this virtue, this power, to be found in the word itself? Perhaps it should be called instead a ‘pivot word’ (Heine 1999, 4): it marks the turning point.
From the Glossary appended to Dogen’s Treasury of the True Dharma Eye:
turning point: 轉処 [tensho]. 轉機 [tenki], literally, turning event. A place where delusion is transformed into enlightenment.— Tanahashi 2010, 1139
Only when you get here will you know (the meaning of the) ancient saying, ‘Mind revolves along with myriad phenomena; the turning point is truly mysterious.’— Blue Cliff Record, Case 22 (Cleary and Cleary 1977, 152)
How to discern the point? Even the Buddhas of the past, present and future, and even the Zen masters over the ages, cannot shoot this black star. How do you shoot it?— Hakuin (Cleary 2002, 4)