Aristotle

==== Dreams ====
{{further | Dream#Other}}

Aristotle describes sleep in ''On Sleep and Wakefulness''.{{sfn| Holowchak | 1996 | pp=405–423}} Sleep takes place as a result of overuse of the senses{{sfn| Shute | 1941 | pages=115–118}} or of digestion,{{sfn| Holowchak | 1996 | pp=405–23}} so it is vital to the body.{{sfn| Shute | 1941 | pages=115–118}} While a person is asleep, the critical activities, which include thinking, sensing, recalling and remembering, do not function as they do during wakefulness. Since a person cannot sense during sleep, they cannot have desire, which is the result of sensation. However, the senses are able to work during sleep,{{sfn| Shute | 1941 | pages=115–18}} albeit differently,{{sfn| Holowchak | 1996 | pp=405–423}} unless they are weary.{{sfn| Shute | 1941 | pages=115–118}}

Dreams do not involve actually sensing a stimulus. In dreams, sensation is still involved, but in an altered manner.{{sfn| Shute | 1941 | pages=115–118}} Aristotle explains that when a person stares at a moving stimulus such as the waves in a body of water, and then looks away, the next thing they look at appears to have a wavelike motion. When a person perceives a stimulus and the stimulus is no longer the focus of their attention, it leaves an impression.{{sfn| Holowchak | 1996 | pp=405–423}} When the body is awake and the senses are functioning properly, a person constantly encounters new stimuli to sense and so the impressions of previously perceived stimuli are ignored.{{sfn| Shute | 1941 | pages=115–118}} However, during sleep the impressions made throughout the day are noticed as there are no new distracting sensory experiences.{{sfn| Holowchak | 1996 | pp=405–423}} So, dreams result from these lasting impressions. Since impressions are all that are left and not the exact stimuli, dreams do not resemble the actual waking experience.{{sfn| Modrak | 2009 | pp=169–181}} During sleep, a person is in an altered state of mind. Aristotle compares a sleeping person to a person who is overtaken by strong feelings toward a stimulus. For example, a person who has a strong infatuation with someone may begin to think they see that person everywhere because they are so overtaken by their feelings. Since a person sleeping is in a suggestible state and unable to make judgements, they become easily deceived by what appears in their dreams, like the infatuated person.{{sfn| Holowchak | 1996 | pp=405–423}} This leads the person to believe the dream is real, even when the dreams are absurd in nature.{{sfn| Holowchak | 1996 | pp=405–423}} In ''De Anima'' iii 3, Aristotle ascribes the ability to create, to store, and to recall images in the absence of perception to the faculty of imagination, ''phantasia''.{{sfn| Shields | 2016}}

One component of Aristotle's theory of dreams disagrees with previously held beliefs. He claimed that dreams are not foretelling and not sent by a divine being. Aristotle reasoned naturalistically that instances in which dreams do resemble future events are simply coincidences.{{sfn| Webb | 1990 | pages=174–184}} Aristotle claimed that a dream is first established by the fact that the person is asleep when they experience it. If a person had an image appear for a moment after waking up or if they see something in the dark it is not considered a dream because they were awake when it occurred. Secondly, any sensory experience that is perceived while a person is asleep does not qualify as part of a dream. For example, if, while a person is sleeping, a door shuts and in their dream they hear a door is shut, this sensory experience is not part of the dream. Lastly, the images of dreams must be a result of lasting impressions of waking sensory experiences.{{sfn| Modrak | 2009 | pp=169–181}}