427a17-19. There are two distinguishing characteristics by which people mainly define the soul: motion in respect of place; and thinking, understanding, and perceiving.
But people or common sense does not define things, but rather, as a simile of a definition, it is faced their power of resisting to the concretion of those facts that compound human life.
To define, horizontai, should be meant as the process by which people receive the limits from the things. The limits are the forms by which the things resist to any reduction that would appear in the common dealing with them.
Aristotle indicates two forms in the case of dealing with living beings: motion in respect of place and, generally speaking, thought. The man or the animal resists to any assimilation by what is called soul, and the forms of resistance are movement and thought.
The resistance is directed against the habit of taking the living beings as things being at our disposal. Such things are considered as items among other ones, all of them constituting our medium of life or our world.
In this case, living things, animals or humans, could be taken into account in a numerical fashion: a number of exemplars or of members of a family, group, citizens etc.
The numerical valuation involves the similar process of naming them through nouns. In fact, living beings are simultaneously numbered and named by nouns.
The resistance of the individual nature of a living being to the dual process of numbering and naming is rather absent.
The resistance comes out when the living beings moves from one place to another. By moving, they show that cannot be circumscribed in one’s life as simple items, together with the places they occupy and left.
Accordingly, they obliged the language to take them into account in other way than that of patient things subdue to the process of naming by nouns. They prove to be causes of their descriptions trough verbs, since they are responsible for the modification of the verbal time and of the linkage with nouns determined by verb.
Hence, they have to be called with a noun that encompasses all the strangeness felt by us whenever the things escape from our control. Therefore, they are called ‘souls’.