I was led down a rabbit hole today by ktschwarz, who linked to this 2011 Log post , whose long comment thread I read with fascination. I was particularly struck by a comment by Suzanne Kemmer which I must have read at the time, since I commented later on, but which I’d completely forgotten in the ensuing decade and a half; since it’s so interesting, I’m reposting it here in the hope of both enlightening the multitudes and remembering it myself: On till death do us part : I’ve researched the various analytic causative constructions in the history of English. The “make” causative as in it made me laugh only started to emerge in Middle English. An older analytic causative, occurring in Old English and persisting through the Middle English period, was [ don (the ancestor of Modern English do ) + (direct object) + INF]. So “it did us laugh” was the normal way of saying “it made us laugh”. Till death do us part means ‘until death causes us to part’. The main verb do is in the subjunctive, to indicate irrealis.…