c. 1500, "times gone by, the time that has preceded the present," from past (adj.). Meaning "a past life, career, or history" is attested by 1836.
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"]
AMERICA does not repel the past, or what it has produced under its forms or amid other politics or the idea of castes or the old religions .... accepts the lesson with calmness ... is not so impatient as has been supposed that the slough still sticks to opinions and manners and literature while the life which served its requirements has passed into the new life of the new forms ... perceives that the corpse is slowly borne from the eating and sleeping rooms of the house ... perceives that it waits a little while in the door ... that it was fittest for its days ... that its action has descended to the stalwart and wellshaped heir who approaches ... and that he shall be fittest for his days. [Whitman, opening of the preface to "Leaves of Grass," 1855]
Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement: and when experience is not retained, as among savages, infancy is perpetual. Those who cannot remember the past are condemned to repeat it. [George Santayana, "The Life of Reason," 1905]
[T]he past cannot be presented; we cannot know what we are not. [Thoreau]
The past is never dead. It's not even past. [Faulkner, "Requiem for a Nun," 1950]
early 14c., "done with, over, existing no more," a variant of passed, past participle of passen "go by" (see pass (v.)). Meaning "gone by, belonging to a time previous to this" is from mid-14c. The grammatical sense of "expressing past action or state" is from 1520s; past participle is recorded by 1775; past tense from 1650s. As a preposition, "beyond in time or position," c. 1300, from the adjective.