In Beyond the Pleasure Principle (1920), Sigmund Freud posits that human existence is marked by a struggle between the sex drive, Eros, and the inclination toward death. In other words, human beings possess an instinctual drive toward pleasure and attempt to shield themselves from possible sources of pain. (It is notable that the work was published shortly after the conclusion of WWI and, in the text, Freud attempts to work through the question of why human existence is marked by great moments of pleasure and unimaginable moments of pain.)
According to Freud there are two primary sources of pain in an individual’s life. First, Freud theorizes that humans have an inclination toward self-preservation, which forces the individual to repress some pleasurable experience. For instance, work is necessary to bring in income for food and shelter; thus, some pleasurable experiences must be repressed in order for work to be accomplished. However, Freud notes that sometimes the pleasure principle, Eros, will prevail, which is often to the detriment of the organism. The second major source of pain, according the Freud, occurs when we want to seek pleasure but are forbidden to do so. When this occurs, we repress these feelings and the source of pleasure becomes an instrument of pain. In order to cope with pain and unfulfilled desires, individuals engage in, what Freud terms, the repetition-compulsion. Here, we attempt to master undesirable events by repeating them. In repeating the event, Freud postulates that the individual takes control of the trauma and avoids neurosis.
In the final section of Beyond the Pleasure Principle, Freud claims that the death drive was the first libidinal drive experienced by living organisms. He reads the tendency toward destruction as a need to return to an earlier state of nonexistence. Organisms tended toward the death drive because it marks a resolution of the tensions experienced by the organism.