c. 1300, "done with, over," from past participle of passen "go by" (see pass (v.)). Past participle is recorded from 1798; past tense from 1813.
"times gone by," 1580s, from past (adj.).
The past is the only dead thing that smells sweet,
The only sweet thing that is not also fleet.
[Edward Thomas, from "Early one morning"]