Although much has been written concerning Calderón's comedia, La vida es sueño, little scholarship exists on his full-length play in relation to the two autos sacramentales of the same title. Those who have undertaken such a study customarily find some slight affinity in the plots and themes of the three plays or a correspondence among the human and allegorical dramatis personae. A few have dismissed the effort to compare by concluding that there is very little, if any, connection. The present study illustrates that there is a close affinity among the comedia and the sacramental plays. Central to the comprehension of Calderón's two autos is the author's focus on God as the main protagonist, and not man, as traditionally held. This is particularly true of the second rendition of the auto in 1673, in which the playwright portrays the full complement of the Trinity with the introduction of three God figures, Poder, Sabiduría, and Amor. These three allegorical figures, which represent one God, always interact onstage in unison, in every phase of the salvation-history story of the Creation, Fall, and Redemption. The role that Poder, Sabiduría, and Amor play in the second version is consistent with another Catholic doctrine, which reflects God's nature: Intelligible Emanation. In accepting Segismundo as the comedia's main protagonist, critics have focused much of their attention precisely around the themes of power, knowledge, and love. Finally, this essay offers a suggestion as to why Calderón chose to return to the theme of "life is a dream" a third time, in the latter part of his career. Calderón viewed dreams as vehicles for poetic inspiration and divine revelation. Furthermore, he perceived himself as being divinely inspired by the Creator to help in bringing about man's salvation by accepting his role as priest and dramatist to instruct and enlighten the vulgo through his dramatic art.