Assertion: prologue | /r/CapableOf | do in play
Facets:
Source sentences:
text: In the context of the preceding and next lines, "(And by that destiny) to perform an act, Whereof what's past is prologue; what to come, In yours and my discharge," Antonio is in essence rationalising to Sebastian and the audience that he and Sebastian are fated to act by all that has led up to that moment, the past has set the stage for their next act, as a prologue does in a play.