The essential idea of man’s fall and salvation is entwined with all manner of subjects taken from history, mythology, and romance.
The first contributed The Conversion of Constantine, the second a host of plays like The Divine Jason, Cupid and Psyche, Andromeda and Perseus, The Divine Orpheus, The True God Pan, The Sacred Parnassus, The Sorceries of Sin (Ulysses and Circe). Romance contributed the fables of Charlemagne and the Twelve Peers, etc.
It is almost needless to say that the most important sources of the autos are the Scriptures and Biblical traditions.
Examples of the former are: The Brazen Serpent, The First and Second Isaac, Baltassar’s Feast, The Vineyard of the Lord (S. Matt. xx. 1). Gedeon’s Fleece, The Faithful Shepherd, The Order of Melchisedech, Ruth’s Gleaning, etc.
An interesting example of the use of tradition is the auto of The Tree of the Best Fruit (El Arbol del Mejor Fruto), embodying the legend that the cross on which Christ died was produced from three seeds of the tree of the forbidden fruit planted on the grave of Adam. There yet remains a large number of plays which cannot be referred to any of the above-mentioned classes.
These are the inventions of the poet’s brain, some of them but a recast of secular plays already popular;[11] others are fresh creations, and are among the most interesting of the autos. Among these are The Great Theatre of the World (El Gran Teatro del Mundo, partly translated by Dean Trench), The Poison and the Antidote (El Veneno y la Triaca, partly translated by Mr. MacCarthy), etc.
No idea, however, can be formed of the autos from a mere statement of their form and subjects; they must be examined in their entirety, and the reader must transport himself back to the spirit of the times in which they were written.
What this spirit was, and how the autos are to be regarded, is admirably expressed by Schack, in his History of the Spanish Drama (iii. p. 251), and of which Mr. MacCarthy has given the following spirited translation:
“Posterity cannot fail to participate in the admiration of the XVIIth century for this particular kind of poetry, when it shall possess sufficient self-denial to transplant itself out of the totally different circle of contemporary ideas into the intuition of the world, and the mode of representing it, from which this entire species of drama has sprung. He who can in this way penetrate deeply into the spirit of a past century will see the wonderful creations of Calderon’s autos rise before him, with sentiments somewhat akin to those of the astronomer, who turns his far-reaching telescope upon the heavens, and, as he scans the mighty spaces, sees the milky-way separating into suns, and from the fathomless depths of the universe new worlds of inconceivable splendor rising up.