Zhuangzi chapter 6: Yan Hui's staged forgetting, culminating in 'I smash up my limbs and body, drive out perception and intellect, cast off form, do away with knowledge, and merge with the great thoroughfare.' Tang dynasty masters, notably Sima Chengzhen, systematized it into the Zuowanglun (c. 700 CE), an actual manual.
The modern framing: zuowang as ancient meditation rebranded for retreats, the Taoist head start on the mindfulness industry. The marketing works; the forgetting of the meditator usually gets left out of the brochure.
The endpoint the passage describes is not calm but subtraction: even the one who forgets is forgotten. In the tradition this is the true arrival of nobody, not hiding from the world but running out of self to hide. Whether that is liberation or dissolution is the debate the text refuses to settle.
If forgetting is the technique, what was remembering protecting?