Date of Award
For a man to live means that he must act. His life is truly a complex pattern of actions, which may be grouped into two classes: first, those actions for which he is responsible, and secondly, those for which he is not responsible. Those actions for which he is the agent but for which he is not responsible are called non-voluntary acts. Man causes them, but he is not their rationally responsible cause. These acts are properly called acts of man. But the second class of acts, those actions which are performed under man's control and for which he can be rightly held responsible are called voluntary acts.
Those two classes of acts are distinguished by the fact that when a man intelligently, freely and willingly performs an act, this act is called a human act. There are many actions about which man makes no rational choice, such as the processes of growth and respiration, and these therefore cannot be called human acts. But for a man to perform a human act, he must know what he is doing, be free to do it, and finally, will to do it. Now everything that acts acts in view of an end. Therefore, when a man performs an act, whether good or bad, he has to know what he wills. The will, although it is the faculty of desire, is in itself blind, and consequently a man cannot desire what he does not know. Thus we have the important ethical principle: "Nothing is willed that is not known." The next requisite for a man to perform a human act is that he will to act. An example of this is afforded in the distinction made between winking and blinking, for when a man winks he wills to do so and thus performs a voluntary act, but when he blinks, this act is involuntary. Therefore when acts are not elicited from the will they are but acts of man and not human acts. For unless man’s acts proceed in some way from his will, they are not truly human and he is not responsible for them.
Caulfield, Terrence, "Virtue In The Philosophy Of St. Thomas Aquinas As Contained In The Summa Theologica" (1948). Philosophy Undergraduate Theses. 67.