To be a materialist is to take the view that thinking creatures are material through and through. This implies three major questions, to which a theory of mind – call it philosophy, psychology, cognitive science – is required to find answers to the following questions: How could anything material be conscious? How could anything material be about anything? and How could anything material be rational? This chapter also talks about Ibn Sina's internal faculties: the common sense, the imagination, the estimative faculty, and the memory. There are two features that Thomas felt needed explaining: the problem of universals, and the problem of intentionality. Both arise if we have a materialistic view of humans, and there is the constant temptation to think that if we drop that view, we will drop the problems with it, though that is dubious.