What if there is no such thing as a real passage of time? What differences would this idea make for our conception of the world and of our lives in the world? Donald A. Crosby's Primordial Time: Its Irreducible Reality, Human Significance, and Ecological Import defends the objective, underived reality of time and its crucial existential and ecological significance by focusing on the qualitative, inner experiences of the passage of time. The time of these inner experiences has often been described as illusory, on the ground that there is no such thing as an objective passage of time. But Crosby argues that the firsthand human experience of time, far from being illusory, provides essential evidence of the reality of it--evidence complemented by close examination of scientific and philosophical indications of the objective reality of time--as against its detractors. Of equal importance is the existential meaning of firsthand experience of the passage of time--meaning apart from which the dynamics of human life collapse into absurdity. Finally, Crosby explores the central, urgent role of the reality of time in relation to the ecological crisis of our day.