Natsume Soseki is best known for his novel Kokoro, a word which literally means "heart", and has shades of meaning which can be translated as "the heart of things" or "feeling". The work deals with the transition from traditional Japanese society to the modern era, by exploring the friendship between a young man and an older man he calls "Sensei" (or teacher). It continues the theme of isolation developed in Soseki's earlier works. Other important themes in the novel include the changing times, the changing roles and ideals of women, and intergenerational change in values, the role of family, the importance of the self versus the group, the cost of weakness, and identity.