Mersault's Conclusion

Mersault has an epiphany at the end of the book, once he realizes that he is definitely going to die and all hope is lost, that life has no meaning. That's why he says it wouldn't matter because Marie would find a new Mersault and Raymond would befriend someone else. His life had no purpose, and it isn't until now that he understood and embraced the full ideaology of existentialism. This discovery is the epiphany.