Why, of the many significant writings of the seventeenth century, do Hamlet, Don Quijote, and La vida es sueño belong together in a comparative study? Certainly not merely because they are the most famous works of Shakespeare, Cervantes, and Calderón, three of the century's most famous men. Beyond doubt, the differences separating them are sharp and obvious: form and technique, style and concept, guiding esthetic impulses of authors who were disparate in their temperament and their lives. But if we fix our attention on the ideological problems embodied in the careers of the three heroes, Hamlet, Don Quijote, and Segismundo, we immediately discern strong bonds of relationship, to the point where not only similarities but even contrasts take on significance, reflecting light from one work upon the other, and finally upon the intellectual outlook and preoccupations of the time.