Hans Jonas (1903-93) was a German Jew, pupil of Heidegger and Bultmann, lifelong friend and colleague of Hannah Arendt at the New School for Social Research, and one of the most prominent thinkers of his generation. The range of his topics never obscures their unifying thread: that our mortality is at the root of our moral responsibility to safeguard humanity's future. Mortality and Morality both consummates and demonstrates the basic thrust of Jonas's thought: the inseparability of ethics and metaphysics, the reality of values at the center of being.