Self-Overcoming and Janus-face.

"Janus-face" is a term that Nietzsche briefly uses in #37 of Human, All Too Human, in a passage that he re-cites in Ecce Homo.  Meaning 'looking both backwards and forwards', it could also apply to the "Moment", in the 'Vision and the Riddle' of Thus Spoke Zarathustra, i. e. to the Present that both looks back on the infinite Past, and looks forward to the infinite Future.  Likewise, the concept of Self-Overcoming, that has been previously proposed here, is Janus-faced, because it combines the past-directed affirmation of Eternal Recurrence and the future-oriented Will to Power.  So, though the phrase has occasionally been misused by commentators to characterize some of Nietzsche's peripheral opinions as merely 'two-faced', the proper connotation of it, i. e. entailing Temporal features, applies, on that analysis, to the very heart of his system.