An example of concept formation might occur when an observer, having noted that instances in which people and animals are frustrated, this in turn causes them to become aggressive. This process of active reason would be seen here because the principle of frustration causes aggression would be distilled or abstracted from experience. This example of concept formation of course fails to capture the participation of the soul in active reason, but it is at least an approximation of what Aristotle meant by active reason.

Aristotle distinguished between active reason and passive reason. Active reason, the highest form of thinking, occurs when a person forms a concept or invents an object of thought through the behavioral processes of abstraction (or concept formation). In contrast, passive reason refers only to the use of previous experience, including previously invented concepts, to achieve some practical purpose. In active reason, a new object of thought (i.e., concept) is born, whereas in passive reason no new object of thought is created.