In "The Unbearable Lightness of Being," Milan Kundera explores the singularity of human life, emphasizing that each individual only experiences life once. This uniqueness means that we lack the opportunity to evaluate our choices against multiple outcomes, as we are confined to one existence with one set of decisions. This perspective leads to a profound uncertainty about the value of our choices.

The inability to revisit and compare different decisions makes it difficult to label any choice as definitively good or bad. Each decision's weight and significance remain elusive, as humans navigate life without the benefit of hindsight from alternative lives. This concept invites readers to reflect on the complexity of life's choices and the inherent struggle to find meaning and direction amid the uncertainty.