The argument of conformity and dissent with respect to generally accepted customs is very vast if one discusses it within the context of the transformative potential of theoretical ethics. Therefore, I will examine one particular aspect of this immense area of study: what does the biographical information available to us tell us about the influence of the theoretical break with conventions and practices on the actual life of ancient philosophers? To what extent does theory have an impact on life? I will examine briefly the case of ancient Pythagoreanism, of Xenophon’s and Plato’s Socrates, of Diogenes the Cynic, of the “mad” Socrates and of Plato. I will try to demonstrate that theoretical innovations within ethics can lead both to the rejection and to the full acceptance of the living as of the practices and traditions in vigour.