How did Aristotle, the founder of scientific biology, define life? In this volume, which collects the contributions to a conference held in 2006, philologists, philosophers and biologists approach this question. They study how Aristotle's concept of the soul relates to his perception of life; how he evaluates the different criteria that, according to him, constitute life; how he uses those criteria to define different organic structures; whether there exists a unified definition of life in Aristotle's philosophy; aspects of procreation and ontogenesis; the relationship between individuals and species; the reception of Aristotle's theories. German text.