In reaffirming the primacy of experience, Nietzsche once again strongly rejects philosophical systems which attempt to find truths or values outside of experience (specifically that of Kant). He returns once more to the idea of productive constraint, offering the example of artists not only as evidence of this concept, but also as proof of the unity of opposites too, as creative freedom emerges from discipline, not in spite of it. Nietzsche’s concept of rank is less clear; his nobility clearly does not align with that of the established (if disempowered) European nobility of his time; instead, it seems to envision something more ephemeral. Unfortunately, the connection between the noble attitude and the inborn nature of nobility is one that Nietzsche leaves unexplained.