In "The Handmaid's Tale," Margaret Atwood illustrates the concept of gradual change through a powerful metaphor about a slowly heating bathtub. This imagery emphasizes how people can overlook or be unaware of harmful transformations in their environment until it is too late for them to react. The process is so subtle that one may not recognize the danger until they are in a precarious situation.

This idea serves as a warning against complacency in the face of gradual societal shifts. Just as a person might not realize they are being cooked in a bathtub until it's fatal, individuals may fail to notice when their freedoms and rights are eroded little by little. Atwood’s message stresses the importance of vigilance and awareness of changes occurring around us to prevent dire consequences.