In this profound philosophical inquiry, Jean-Paul Sartre delves into the pervasive nature of deep sadness, examining its roots within the human condition and existential experience. The work explores how the burden of radical freedom, the absence of inherent meaning, and the confronting of one's own mortality can manifest as an inescapable anguish. Sartre meticulously unpacks the feeling of 'deep sadness' not merely as an emotion, but as a fundamental aspect of human consciousness in a world devoid of predetermined purpose. Through sharp analysis, he challenges readers to confront the source of their despair and embrace the responsibility that comes with absolute freedom, ultimately suggesting a path toward authentic living despite the inherent melancholy of existence.