The authors of this paper attempt to uncover a possible relationship between Calderon de la Barca and Borges, based on the hypothetical question whether or not the argentine writer read Calderon's plays. They analyze two key concepts in both writers: the phrase La vida es sueno and the problem of free will, describing the different visions of Calderon and Borges. It all ends with an open conclusion: there are more concomitants than those that the reader may find at first glance.