The metaphysical claim being made by Heidegger-Nietzsche is that reality consists in Process and Becoming, not in the static absolute Being that exists only because our minds need something to hold on to in mid stream. Things continually emerge into being. The activity of our senses (itself a practice of art) continually discloses things.The piece emphasizes where they agreed more than their differences, but is perhaps more informative that way. Read the whole thing.