 Medieval theories of intentionality – not to mention more recent philosophers influenced by these theories, such as Brentano (1874 [1995]) – draw their inspiration from Aristotle’s theory of perception and thought, in particular his doctrine that in cognition the form of the sensible or intelligible object is “received without the matter” (On the Soul II 12, 424a17–24; III 2, 425b23–24; III 4, 429a15–19; and III 8, 431b26–29) and the doctrine that the object, or more precisely its activity as an object of cognition, is “one and the same” as the activity of cognition and is present in the cognizing subject (III 2, 425b25–426a27). Both perception and thought are intentional states, and Aristotle’s analyses of them are central to his psychological theory as a whole. But none of these passages gives clear evidence of Aristotle’s awareness of the problem of intentionality, much less provides a definition of intentionality or any of its essential features. To begin with, each doctrine applies to more than just intentional states. The impression of signet ring in sealing wax is offered not merely as an analogy, but as a genuine example of a form’s being received without the matter, a point accepted even by commentators such as John Philoponus and Thomas Aquinas; Philoponus also mentions images in mirrors as another example (Philoponus, On Aristotle’s On the Soul, 444.17–26, 437.19–25; Thomas Aquinas On Aristotle’s On the Soul 2.24, 56–59 = §554). This doctrine cannot therefore provide a sufficient condition for intentionality, still less for cognition or awareness. Similarly, Aristotle defends his claim that the object’s activity is one and the same as the activity of cognition and present in the cognizing subject as simply an instance of a much wider causal generalization: in every causal interaction, including inanimate and noncognitive ones, the activity of the agent is one and the same as the activity of the patient and occurs in the patient (On the Soul III 2, 426a2–11). Further, neither of these doctrines holds for all intentional states: each fails to apply to paradigmatic cases of intentionality, like dreams or future hopes, where the problem of intentionality is most palpable. So neither doctrine provides a necessary condition for intentionality either. They are rather general causal doctrines that apply to a special class of intentional states, like perception and thought, where the intentional state is about what brings it about – that is, it is about its own cause – something that is not true of intentional states in general. Even if they prove to be central to his theory of intentionality, they do not directly address the problem as such.