In contemporary Nietzschean scholarship, some interpreters have emphasized the will to power as a psychological principle because Nietzsche applies it most frequently to human behavior. However, in Nietzsche's unpublished notes (later published by his sister as "The Will to Power"), Nietzsche sometimes seemed to view the will to power as a more (metaphysical) general force underlying "all" reality, not just human behavior—thus making it more directly analogous to Schopenhauer's will to live. For example, Nietzsche claims the ""world is the will to power—and nothing besides!"". Nevertheless, in relation to the entire body of Nietzsche's published works, many scholars have insisted that Nietzsche's principle of the will to power is less metaphysical and more pragmatic than Schopenhauer's will to live: while Schopenhauer thought the will to live was what was most real in the universe, Nietzsche can be understood as claiming only that the will to power is a particularly useful principle for his purposes.