These [bad effects of pleasure and pain] are the reason why people actually define the virtues as ways of being unaffected and undisturbed [by pleasures and pains]" (1104b21-25) It is not imperative to remain indifferent or unaffected by both pleasure and pain to be virtuous, it is only essential that we have the right feelings of pleasure and pain at the right time. Therefore, he goes on defining virtue as the right state in front of pleasure and pain:

We assume, then, that virtue is the sort of state that does the best actions concerning pleasures and pains, and that vice is the contrary state."(1104b26-27)

Thus, Aristotle sums up his discussion and concludes that virtue is all about the feelings of pleasure and pain, and that the actions, even if they are good can decrease virtue when they are done badly:

To sum up: Virtue is about pleasures and pains; the actions that are its sources also increase it or, if they are done badly, ruin it; and its activity is about the same actions as those that are its sources."(1105a15-16)

Hursthouse also summarizes Aristotle's theory about virtue in the same way, asserting that the appropriate feelings are actually what define an action as virtuous:

And, according to virtue ethics, the agent with the inappropriate feelings does not act virtuously, in the very way or manner that the virtuous agent acts."(Hursthouse, 125)

The theory Aristotle proposes of virtue is continued by his definition of the human soul and its 'contents'. He argues that the virtue is a state of soul and of the individual,...

The virtue of eyes, for instance, makes the eyes and their functioning excellent, because it makes us see well; and similarly, the virtue of a horse makes the horse excellent, and thereby good at galloping, at carrying its rider, and at standing steady in the face of the enemy. If this is true in every case, the virtue of a human being will likewise be the state that makes a human being good and makes him perform his function well. (1105b30-1106a)
His comparison of the virtuous character of a man with the 'virtue' of the eyes that make one see well indicates that he considers virtue as the state of soul that determines the proper 'functioning' of the individual, that is, that which makes him perform the best actions.

In this way, we see that for Aristotle the optimal actions of a certain human being are the result of the virtuous character, which is in fact, a state of the soul. The virtuous character is in its turn, determined by the other states, or the feelings of pleasure and pain experienced in a certain situation or when performing a particular action. His implication is that no action is good of itself, unless supported by the proper feelings, and that this would be the essence of ethics.

Works Cited

Aristotle. Nicomachean Ethics. Indianapolis: Hackett Publishing, 1985

Hursthouse, Rosalind. On Virtue Ethics. Oxford: Oxford University Press, 1999