in which the soul talks to itself. Platonic forms are seen as universals that exist in a changeless realm different from the sensible world. Examples include the forms of goodness, beauty, unity, and sameness. On this view, the difficulty of thinking consists in being unable to grasp the Platonic forms and to distinguish them as the original from the mere imitations found in the sensory world. This means, for example, distinguishing beauty itself from derivative images of beauty. One problem for this view is to explain how humans can learn and think about Platonic forms belonging to a different realm. Plato himself tries to solve this problem through his theory of recollection, according to which the soul already was in contact with the Platonic forms before and is therefore able to remember what they are like. But this explanation depends on various assumptions usually not accepted in contemporary thought. Aristotelianism and conceptualism Aristotelians hold that the mind is able to think about something by instantiating the essence of the object of thought. So while thinking about trees, the mind instantiates tree-ness. This instantiation does not happen in matter, as is the case for actual trees, but in mind, though the universal essence instantiated in both cases is the same. In contrast to Platonism, these universals are not understood as Platonic forms existing in a changeless intelligible world. Instead, they only exist to the extent that they are instantiated. The mind learns to discriminate universals through abstraction from experience. This explanation avoids various of the objections raised against Platonism. Conceptualism is closely related to Aristotelianism. It holds that thinking consists in mentally evoking concepts. Some of these concepts may be innate, but most have to be learned through abstraction from sense experience before they can be used in thought. It has been argued against these views that they have problems in accounting for the logical form of thought. For example, to think that it will either rain or snow, it is not sufficient to instantiate the essences of rain and snow or to evoke the corresponding concepts. The reason for this is that the disjunctive relation between the rain and the snow is not captured this way. Another problem shared by these positions is the difficulty of giving a satisfying account of how essences or concepts are learned by the mind through abstraction. Inner speech theory Inner speech theories claim that