The title of Life Is a Dream (La vida es sueño) expresses the central idea of the play. In the most simplistic and literal terms, the audience knows more than the characters, being aware, for instance, that Segismund is not dreaming in act 2, when Clotaldo later assures him that he was, or in act 3, when he believes he might be. Any sense of certainty, however, comes under philosophical attack in act 4, when Segismund questions how anyone can ever be sure they are not dreaming. Perhaps all of life is a dream.

The Catholic background to Calderón’s work is of vital importance here. Segismund ends the play by saying that the dream in which everyone lives will only be dispelled by “the Last Trumpet of the eternal Day.” In this sense Segismund stands as synecdoche for the whole of humanity. The life that everyone has been trained to accept as real is nothing but an illusion when compared with the ultimate and eternal reality of heaven. Life serves much the same function in God’s plan as Segismund’s brief appearance at court served in act 2 of the play: it determines whether one is worthy of heaven or not.

The audience or reader of the play starts out with the certainty that Segismund is being deceived. He is told he is dreaming and later decides that he might be, when in fact all these things happen when he is wide awake. By the end of the play, however, Segismund may have convinced the audience that everything presented to them was an illusion. This works as a metatheatrical conceit—since a play is an illusion—but also invites them to question the reality, certainty, and stability of their everyday lives.

This theme is more prominent in the version of the play in which Clotaldo turns out to be Rosaura’s father (rather than a friend of her father, as here). However, the main plot still provides ample exploration of the theme, particularly in the question of Basilio’s actions toward Segismund and whether the father is responsible for the actions and disposition of his son.

Even before Segismund raises this question in act 2, Basilio has reproached himself with it. The audience may well agree with Segismund that it is rather late for the thought to occur to Basilio that chaining his son up alone in a remote dungeon for twenty years may not have improved his temper or made him well-suited to wield power.

When Basilio enters the throne room in act 2, the first observation Segismund makes is that he has no feelings for this old man. He can see from his crown that Basilio is the king, but nothing tells Segismund that this is his father. This is scarcely surprising, since Basilio has played no part in Segismund’s upbringing, has robbed him of his birthright, and has chained him up “like a wild beast’s whelp” rather than a prince.

It is only at the end of the play that Basilio recognizes Segismund’s outstanding qualities and talents, from his courage and prowess in battle to his intelligence and rationality. These attributes make it clear that Segismund is correct to conclude that Basilio misread the stars, or blamed them for his own prejudice, and that he himself created the defects he deplored in his son earlier in the play.

The theme of what honor demands is the one that ties the plot and the subplot together most completely. Rosaura is the character most entirely motivated by honor, and Astolfo the character most lacking in it. It may...