The will to power:

"Precisely if all views of the world are interpretations, i.e. acts of the will to power, the doctrine of the will to power is at the same time an interpretation and the most fundamental fact, for, in contradistinction to all other interpretations, it is the necessary and sufficient condition of the possibility of any 'categories'." (Source: Leo Strauss, "Note on the Plan of Nietzsche's Beyond Good and Evil".)

The eternal recurrence:

"In the new wisdom of Zarathustra, the wise man, the spirited knower, is a lover who transforms the beloved [the world as will to power] into something still more beautiful than she is [namely, into the world as eternally recurring will to power], and she is beautiful as she is." (Source: Laurence Lampert, Nietzsche's Teaching, page 120.)

The Superman:

"[T]his kind of man that he [Zarathustra] conceives, conceives reality as it is: it is strong enough for that—, it is not estranged from it, not engrossed in something different from it, it is reality itself, it contains even all its frighteningness and questionableness, only with that can man have greatness..." (Source: Nietzsche, Ecce Homo, "Why I Am a Destiny", section 5; my translation.)