Of the bow and lyre: Nietzsche's theory of eternal recurrence

Nietzsche's theory of eternal recurrence loosely describes a cyclical repetition of all events. This may, on the face of it, appear odd: how are we to understand eternal recurrence in the context of his broader philosophy? My understanding of eternal recurrence has three primary characteristics. First, that eternal recurrence is beyond will to power in that it subsumes the opposition between will to power (i.e.: affirmation, creativity) and will to nothingness (i.e.: negation, nihilism). Second, that eternal recurrence is an existential necessity. By existential necessity I mean that it is not itself a vital force or will but a necessary condition for vital forces or wills. Finally, that the existential necessity of eternal recurrence takes the form of the commitment of life to the perpetual fluidity of all things in time.