Mersault is so completely detached from feeling the highs and lows of life that even the blazing hot sun can set him off into murderous action. He seems to only know what interests him after he has lost it. He knows what he doesn’t like, and that list is seemingly endless, but he is too immersed in the belief that everything is pointless, so why even bother, that he is out of place and misunderstood every where he goes.
Ultimately though, he is able to realize what it is that he is drawn to. His memories of swimming on the beach, of enjoying a film and spending time with Marie. He is able to cherish the moments of beauty amidst the banality and indifference of life — and of death.