 " Within " was a story milestone for the series . It introduced several new character changes for the season , including the departure of Mulder and the inclusion of Doggett as a main character to the cast . The episode was written as a way to both explain Mulder 's absence as well as appease fans who would otherwise lament the loss of Duchovny . " Within " also marked the first major change to the opening credits since the show first started , with new images and updated photos for David Duchovny and Gillian Anderson , and the addition of Robert Patrick . " Within " has been analyzed due to its themes of death and resurrection . In addition , the experiments performed on Mulder after his abduction have been thematically compared to the Crucifixion of Jesus . 
