  Moreover, not all content deriving from the intellectual faculty  is “pure.” In Descartes' scheme, there are only two powers of mind: the intellect and the will (Med. IV,  Princ. I.32–4). The  intellect is the power of perception or representation. Acts of pure intellect occur without the need for any accompanying brain processes; these are purely intellectual perceptions. But there are other intellectual acts that require the presence of the body: sense perception, imagination, and corporeal (body-involving)  memory. These intellectual acts are less clear and distinct than acts of pure intellect, and may indeed be obscure and confused (as in the case of color sensations). Nonetheless, the will may affirm or deny such content. As discussed in the next subsection, error can arise in these judgments.