common to all people, or common to various types of animals. There is also difficulty with trying to determine whether the common sense is truly separable from the individual sense perceptions and from imagination, in anything other than a conceptual way as a capability. Aristotle never fully spells out the relationship between the common sense and the imaginative faculty (, ), although the two clearly work together in animals, and not only humans, for example in order to enable a perception of time. They may even be the same. Despite hints by Aristotle himself that they were united, early commentators such as Alexander of Aphrodisias and Al-Farabi felt they were distinct, but later, Avicenna emphasized the link, influencing future authors including Christian philosophers. argues that Aristotle used the term "common sense" both to discuss the individual senses when these act as a unity, which Gregorić calls "the perceptual capacity of the soul", or the higher level "sensory capacity of the soul" that represents the senses and the imagination working as a unity. According to Gregorić, there appears to have been a standardization of the term as a term for the perceptual capacity (not the higher level sensory capacity), which occurred by the time of Alexander of Aphrodisias at the latest. Compared to Plato, Aristotle's understanding of the soul () has an extra level of complexity in the form of the or "intellect"—which is something only humans have and enables humans to perceive things differently from other animals. It works with images coming from the common sense and imagination, using reasoning (, ) as well as the active intellect. The identifies the true forms of things, while the common sense identifies shared aspects of things. Though scholars have varying interpretations of the details, Aristotle's "common sense" was in any case not rational, in the sense that it implied no ability to explain the perception. Reason or rationality () exists only in man according to Aristotle, and yet some animals can perceive "common perceptibles" such as change and shape, and some even have imagination according to Aristotle. Animals with imagination come closest to having something like reasoning and . Plato, on the other hand was apparently willing to allow that animals could have some level of thought, meaning that he did not have to explain their sometimes complex behavior with a strict division between high-level perception processing and the human-like thinking such