This book is an investigation that covers the problems concerning the constitution of Nature, Destiny, Theology, Psychology, Ethics and moral responsibility in Stoicism. All this having as a common thread of the developed argumentation the question of whether the human being is a participant or not of nature, and if, therefore, the Stoic formula for virtue, "to live in accordance with nature", implies or not the existence of an autonomous or heteronomous agent, morally responsible or not for his actions.