For the Stoics there are no evil acts in themselves, but the moral sea lies in a deprivation of the right order in the human will. Opposites are implicated: justice cannot be understood without injustice.
The Stoics paid great attention to the problems of behavior. The end of life, happiness, consists in achieving virtue in its stoic sense (living according to the Law of Nature). For man, since the universe is governed by a Natural Law, conforming to the laws of the universe in the broad sense and adapting his behavior to his own essential nature to reason, form a unity. For the first Stoic philosophers, it is therefore a “Nature”, later they would conceive it from an anthropological point of view. But in any case, living according to nature meant adhering to the principle that operates in nature from which the human soul was not excluded.
A practical moral doctrine is already observed in Seneca. Stoicism is valued for the benefits that its principles are capable of conferring on a man's mental state and the conduct of his life.
For Diogenes Laerecio virtue means living in accordance with nature which in the case of man is understood as a life according to reason since man is a rational being who has the privilege of knowing natural laws and accepting them consciously. Man is therefore free to change his inner attitude.
No action is in itself good or bad, determinism leaves no room for this differentiation. Only virtue is good. What is neither virtue nor vice cannot be considered good nor bad but indifferent. They are for the Stoics cardinal virtues:
But definitely virtuous behavior only day be reached by the sage, absolutely free of passions.
Pleasure could not be considered an end in itself but a result or what accompanies certain activities. Thus, rigorous moral idealism characterizes the first stoicism, while the notion of progress would be more emphasized later, encouraging man to move the path of virtue to remain in it.