In Albert Camus' novel "The Stranger," the opening line reflects the protagonist Meursault's emotional detachment from the world around him. His uncertainty about his mother's death—whether it occurred today or yesterday—illustrates his disconnection from reality and the conventional expectations of grief. This ambiguous sentiment sets the tone for the existential themes that permeate the story, highlighting a life lived without deeply felt emotions or societal norms.

Throughout the narrative, Meursault's indifferent attitude toward significant events, including his mother's passing, challenges traditional notions of morality and human connection. His actions and thoughts provoke readers to question the meaning of life and the judgments society imposes on individuals. By exploring Meursault's perspective, Camus delves into existential philosophy, emphasizing the absurdity of existence and the complexities of human experience.