St John of Damascus: Concerning what is Voluntary and what is Involuntary.

Concerning what is Voluntary and what is Involuntary.

The voluntary implies a certain definite action, and so-called involuntariness also implies a certain definite action. Further, many attribute true involuntariness not only to suffering, but even to action. We must then understand action to be rational energy.

Actions are followed by praise or blame, and some of them are accompanied with pleasure and others with pain; some are to be desired by the actor, others are to be shunned: further, of those that are desirable, some are always so, others only at some particular time. And so it is also with those that are to be shunned.
Again, some actions enlist pity and are pardonable; others are hateful and deserve punishment.

Voluntariness, then, is assuredly followed by praise or blame, and renders the action pleasurable and desirable to the actor, either for all time or for the moment of its performance. Involuntariness, on the other hand, brings merited pity or pardon in its train, and renders the act painful and undesirable to the doer, and makes him leave it in a state of incompleteness even though force is brought to bear upon him.

St John of Damascus