While much attention has been lavished on Friedrich Nietzsche’s earlier and later works, those of his so-called middle period have been generally neglected, perhaps because of their aphoristic style or perhaps because they are perceived to be inconsistent with the rest of his thought. This book gives this section of Nietzsche’s oeuvre its due, offering analysis of the three works that make up the philosopher’s middle period: Human, All too Human; Daybreak; and The Gay Science. It is Nietzsche himself who suggests that these works are connected, saying that their “common goal is to erect a new image and ideal of the free spirit.” The book argues that in their more favorable attitude toward reason, science, and the Enlightenment, these works mark a sharp departure from Nietzsche’s earlier, more romantic writings and differ in important ways from his later, more prophetic writings, beginning with Thus Spoke Zarathustra. The Nietzsche these works reveal is radically different from the popular image of him and even from the one depicted in much of the secondary literature; they reveal a rational Nietzsche, one who preaches moderation instead of passionate excess and Dionysian frenzy. The book concludes with a wide-ranging examination of Nietzsche’s later works, tracking not only how his outlook changes from the middle period to the later but also how his commitment to reason and intellectual honesty in his middle works continues to inform his final writings.