Nietzsche was personally more philosophical than his philosophy. His talk about power, harshness, and superb immorality was the hobby of a harmless young scholar and constitutional invalid. He did not crave in the least either wealth or empire. What he loved was solitude, nature, music, books. But his imagination, like his judgment, was captious; it could not dwell on reality, but reacted furiously against it. Accordingly, when he speaks of the will to be powerful, power is merely an eloquent word on his lips. It symbolises the escape from mediocrity. What power would be when attained and exercised remains entirely beyond his horizon. What meets us everywhere is the sense of impotence and a passionate rebellion against it.
source
George Santayana, Egotism In German Philosophy (1915), Chapter XII