The book covers both better- and lesser-known areas of Friedrich Nietzsche's life and philosophy.

It is notable both for its suggestion of Mencken's still-developing literary talents at the age of 27 and for its impressive detail as the first book written in English on Nietzsche, only seven years after his death, when there were few reliable interpretations of Nietzsche in the Western sphere of letters.

Mencken prepared for writing this book by reading all of Nietzsche's published philosophy, including several works in the original German.

Mencken also often – albeit unintentionally – permitted his personal biases (especially his own views on social Darwinism and, potentially, antisemitism) to influence his interpretations;[3] for instance, he erroneously equated Nietzsche's "will to power" with Arthur Schopenhauer's "will to live."

Mencken's immersion in and enthusiasm for his subject may mark the beginning of "Nietzsche Studies" in America.