Don't tell us you're surprised, folks—after all, memories literally are the whole movie. Eternal Sunshine of the Spotless Mind takes place within the memories of Joel; it's a movie that explores how and why we remember things—and the impact that these memories have on our lives. It's also about what happens when these memories disappear: does the self created by these memories also go away?
Joel's firsthand experience with his own past gives him personal insight into who he is and what he and Clementine had together when things were going well. But over the course of the movie, even his memories of memories are washed away, and he becomes like a blank slate, ready to move out in the world and relive the last two years of his life.
Questions About Memory and the Past
Does Joel ever truly recognize his flaws when he sees himself in his memories?
Does dream-Clementine act like real-Clementine, or has she been tainted by the bias of Joel's memory?
If Joel and Clem both had their memories restored, do you think they would still want to be together? Does the good outweigh the bad in their relationship?
Chew on This
The flaw of Lacuna's process is that the memories must be erased. If Lacuna could simply remind people what their past experiences were like without getting rid of them, their treatment would lead to happier, healthier individuals.
The only reason Joel decides he wants to save his memories of Clem is that he has forgotten all the bad memories already.