stylistic:tone
Theatrical innovator

Calderón initiated what has been called the second cycle of Spanish Golden Age theatre. Whereas his predecessor, Lope de Vega, pioneered the dramatic forms and genres of Spanish Golden Age theatre, Calderón polished and perfected them. Whereas Lope's strength lay in the spontaneity and naturalness of his work, Calderón's strength lay in his capacity for poetic beauty, dramatic structure and philosophical and theological depth. Calderón was a perfectionist who often revisited and reworked his plays, even long after they were first performed.

His perfectionism was not just limited to his own work: several of his plays adapt and reimagine existing plays or scenes by other dramatists, improving their depth, complexity, and unity. Calderón excelled above all others in the genre of the "auto sacramental", in which he showed a seemingly inexhaustible capacity to giving new dramatic forms to a given set of theological and philosophical constructs. Calderón wrote 120 "comedias", 80 "autos sacramentales" and 20 short comedic works called entremeses.

As Goethe notes, Calderón tended to write his plays by taking extra special care of their dramatic structure. He therefore usually reduced the number of scenes in his plays as compared to those of Lope de Vega, so as to avoid any superfluidity and present only those scenes essential to the play, also reducing the number of different metres in his plays for the sake of gaining a greater stylistic uniformity.

Calderón realized that any play was a work of fiction, and that the structure of the baroque play was entirely artificial. He therefore, probably influenced by Cervantes, made regular use of metafictional techniques, such as making his characters joke about the clichés they are expected to slavishly follow.

Most famously in his masterpiece, La Vida es Sueño, Calderón uses an astrological prophecy made decades before the beginning of the play as a way to deliberately mislead the audience about how the plot will unfold. Calderón intended to subtly defend the Catholic doctrine of free will against the Calvinist doctrine of predestination and to depict the unwritten nature of each individual's future based on their choices.

Although his poetry and plays leaned towards culteranismo, Calderón usually reduced the level and obscurity of that style by avoiding metaphors and references that uneducated viewers would not understand. However, he had a great influence anyway in later centuries upon Symbolism, for example by making a fall from a horse a metaphor for a fall into disgrace or dishonour.