The soul is actuality in the way that scientific knowledge is, not in the way that active contemplation is, as shown by the analogy with sleep and waking.

By Aristotle, from On the Soul

Key Arguments

  • He distinguishes two modes of actuality: 'as scientific knowledge is... and as contemplating is'.
  • He notes that 'both sleep and waking depend on the presence of the soul; waking is analogous to contemplating, and sleep to | 412 a 25 | having but not actualizing [scientific knowledge]'.
  • In sleep, the living being still has life and the soul but is not exercising its capacities, which would be impossible if the soul were actuality in the 'contemplating' sense only.
  • He emphasizes temporal priority: 'in the same individual scientific knowledge is prior in coming to be', making it an appropriate model for the soul’s status as a first actuality that underlies further activities.
  • From these parallels he infers that the soul’s actuality is like 'having knowledge' rather than like 'currently using knowledge'.

Source Quotes

146 Therefore, it is the actualization of such a body. But something is said to be actual in two ways, either as scientific knowledge is or as contemplating is. And it is evident that it is as scientific knowledge is.
But something is said to be actual in two ways, either as scientific knowledge is or as contemplating is. And it is evident that it is as scientific knowledge is. For both sleep and waking depend on the presence of the soul; waking is analogous to contemplating, and sleep to | 412 a 25 | having but not actualizing [scientific knowledge]; and in the same individual scientific knowledge is prior in coming to be.
And it is evident that it is as scientific knowledge is. For both sleep and waking depend on the presence of the soul; waking is analogous to contemplating, and sleep to | 412 a 25 | having but not actualizing [scientific knowledge]; and in the same individual scientific knowledge is prior in coming to be. 147 That is why the soul is the first actualization of a natural body that has life potentially.

Key Concepts

  • But something is said to be actual in two ways, either as scientific knowledge is or as contemplating is.
  • And it is evident that it is as scientific knowledge is.
  • For both sleep and waking depend on the presence of the soul; waking is analogous to contemplating, and sleep to | 412 a 25 | having but not actualizing [scientific knowledge]; and in the same individual scientific knowledge is prior in coming to be.

Context

Middle of II.1 (around 412a20–27), where Aristotle refines his definition of soul as actuality by specifying which of his two senses of actuality applies, using the phenomena of sleep and waking.