Full Idea
The faculties of willing, sensing, understanding and so on cannot be called "parts" of the mind, since it is one and the same mind that wills, senses and understands.
Gist of Idea
Faculties of the mind aren't parts, as one mind uses them
Source
René Descartes (Meditations [1641], §6.86)
Book Reference
Descartes,René: 'Discourse on Method/The Meditations', ed/tr. Sutcliffe,F.E. [Penguin 1968], p.164
A Reaction
It is best here to say that Descartes has confused the 'mind' with the 'person'. These faculties make (I think) no sense without a person to perform them, but the 'mind' surely includes these conscious activities, and many fringe events as well.