The enthusiasm Nietzsche expresses in this passage is for eugenics, a theory of biological determinism invented by Francis Galton, Charles Darwin’s first cousin. However extreme Nietzsche’s recommendation might sound today, by the first part of the twentieth century eugenics came to be widely practiced. In 1933, little more than thirty years after Nietzsche’s death, the Hereditary Health Courts set up in Nazi Germany were enforcing a rigorous policy of enforced sterilization; to a lesser degree, similar policies were carried out in societies from the United States to Scandinavia. In 1912, in his presidential address to the First International Congress...