In Ian McEwan's novel "Saturday," the protagonist struggles with the concept of identity and the effects of mental decline. The idea of a deteriorating mind is illustrated through the protagonist's disconnection from a continuous sense of self, leading to a fragmented perception of reality. This disconnection causes a diminished concern for others' opinions regarding their inconsistencies and erratic behavior.

The quote emphasizes the unsettling nature of losing one's identity and the implications it carries in social relations. As the mind degenerates, the ability to maintain a coherent sense of self weakens, showcasing how this loss impacts not only the individual but also their interactions with the world around them.