The contemporary Mandarin particle le is rather polysemous and has a complicated history (Sun & Bisang 2020, § 3.1.3 and Wiktionary) which will here be simplified. The Middle Chinese verb 了 liǎo ‘finish’ takes a clausal complement P, which it follows. Thus, its basic meaning is ‘P is finished’. Phonological erosion produces the particle le. In the first step of grammaticalization, le ends a first clause and indicates change of state; in other words, it implies that the next predication will be about a different situation ().

In the next step, le directly follows a verb. There it signals completion, thus, perfective aspect ().