“Life” is undoubtedly considered aslebes one of the most important fundamental values today; this is also reflected in the very successful efforts to combat diseases and extend life expectancy. In the history of mankind, this was not always the case. From antiquity to the High Middle Ages, only the lives of the free and noble were highly valued. The term does appear in modern philosophy, but it in the 20th century it gained central importance in the list of fundamental values, primarily through the writings of Albert Schweitzer. In addition to this historical-ideological outline (which also presents the social reasons for the lack of high esteem for the lives of all people in earlier times), this chapter provides a comprehensive definition of life valid for bio- and social sciences. According to this, the essence of life lies in the chance and ability for self-determined activity. Then, central questions in this context are discussed: the meaning of life; the question of whether the value of life is questioned by suicide and moribundity; the significance of children today as another indicator of the high valuation of life; and the value of the lives of animals and a life-suitable environment.