Levinson refers to Daniel Levinson, an American psychologist known for his work in adult development. He proposed the Seasons of a Man's Life theory, which outlines the stages individuals go through from youth to old age. His research emphasizes the importance of life transitions and how they shape personal growth and identity. Levinson's theory includes key concepts such as the Life Structure, which represents the underlying pattern of a person's life at any given time. His work has influenced various fields, including psychology, counseling, and education, providing insights into how people navigate their life journeys.