In the beginning of Book II of De Anima, Aristotle describes first-order actuality as “the manner of knowledge” and the second-order actuality as “the manner of the act of contemplating” (412a12). Aristotle gives a first-order and a second-order classification that differentiates the being-at-work-staying-itself-ness of plants, animals and human beings. Some organisms, plants, and animals are able to acquire and recollect knowledge about its genetic information, actions based on memory, and reflexes. Contemplative abilities on the other hand, are abilities that beings with cognition possess. Because second-order beings have the ability to contemplate, they can assign forms to objects (410b). Such as the way human beings assign the form chair to an object made out of wooden pieces constructed in a certain manner.

First-order of actuality encompasses all the basic forms of bodies with a soul, such as plants and certain types of animals. First-order actualities are capable of the following; first, being a this by encompassing the same form from another this, made of the same material that would allow it to be considered a this; and lastly, have a form that allows an actuality to not be considered formless (412a5). A plant for example, is considered to be a first-order actuality since it is capable of growing to something similar to its parent, consist of vegetative cells, and not fail to exist. One thing that first-order actualities lack is the ability to contemplate about other beings with which they have similarities, or realizing that they are beings just like other beings who have a being-at-work-staying-itself within their form.

Second-order actualities on the other hand, are beings capable of contemplating. Aristotle gives a perfect example of the act of contemplation where it is active when the soul is awake but “not put to work” when asleep (412a30). Living beings with second-order actualities when asleep, continue to have the power of contemplation within their capacities, even if they may appear to not have it. Perhaps in a sleeping state they temporarily posesses a first-order actuality.

In Book I, Aristotle mentions that beings are made out of many smaller parts but this raises a question on whether these individual parts continue to have a part of the soul within them even if they were to be separated (411b16). The first-order and second-order descriptions of the soul factor in Aristotle’s definition of the soul in a way that, it defines that individual parts of a being would not have a soul since individually, the separates don’t have the being-at-work-staying-itself ability in them (413a).