The young man in Goya’s famous “The Sleep of Reason Produces Monsters” is alone. With no one around to disturb him, he has fallen asleep while working at his desk. Yet, while this young man is in a state of solitude, he does not seem to be quite alone, for he is surrounded by the wonderful and terrifying products of his mind. Goya’s aquatint is accompanied by a short epigraphy, which reads “imagination abandoned by reason produces impossible monsters: united with her, she is the mother of the arts and the origin of their marvels (La fantasía abandonada de la razón produce monstruos imposibles: unida con ella es madre de las artes y origen de las maravillas).” But how, exactly, can our imagination act in this way? And under what conditions? Would this young man’s imagination produce such impossible monsters had he not been alone? Could it be, then, that our imagination produces terrifying creatures not only when abandoned by reason but also when abandoned by other people?
It is commonly argued that Goya is expressing here the Enlightenment ideals of reason and rationality. Yet, the basic sentiment that motivates the “Sleep of Reason” and the idea that “imagination abandoned by reason produces impossible monsters” is as old as the concept of imagination itself. It can be traced back to the earliest attempts to theorize the cognitive and epistemological roles of the imagination and it remains common throughout most of the history of philosophy, at least until the eighteenth century.
In this short essay, I would like to investigate this idea of the “Sleep of Reason” and of imagination’s capacity to produce impossible monsters when abandoned by reason. Turning to the history of philosophy and science, I am interested here in how philosophers, scientists, doctors, and theologians have thought about the nature of imagination, its relationship to reason, and its ability to radically depart from reality and produce wonderful, incredible, and terrifying images and appearances. Importantly, I seek not only to understand the effect that the abandonment of reason has on the imagination but also to explore this relationship between reason and imagination in the context of loneliness. I would like to ask why we are likelier to be “abandoned by reason” when we are alone, or why the imagination is prone to produce such terrifying images under the condition of solitude.
The first question, then, is why does the imagination, when abandoned by reason, produce impossible monsters? Throughout the history of philosophy and science, the first and most straightforward answer to this question is that the imagination, in itself, is fallible and prone to error. For Plato, the imagination (phantasia or eikasia) is the mental faculty that process the impressions of phantoms (phantasmata) or likenesses (eikones). The instability and fallibility of this faculty are tied both to the imperfection of our senses—on which it depends—and to the inherent and natural instability and imperfection of the objects of sensual perception. Aristotle had a broader—and significantly more influential—understanding of the cognitive and epistemological roles of imagination. For him, the imagination (phantasia) is present in nearly all mental activity: from processing sensual input and providing the foundation for abstract thinking to motivating any kind of animal movement and a broad range of emotions. Yet, unlike the so-called ‘proper senses’ or reason, phantasia could be either right or wrong and is often associated by Aristotle with dreams, hallucinations, and error more generally.
The imagination is not unique to humans. In fact, many animals are guided and “live by” this faculty. Yet humans, according to a common argument, are distinguished from animals by the presence of reason in their soul or mind and by its simultaneous operation with the imagination. Gregor Reisch expressed this idea in his 1503 Margarita Philosophica, arguing that “in man this power [phantasia] is adorned with reason” whereas “in brutes, by contrast, the phantasy is ruled by the instinct of nature.” Giovanni Francesco Pico della Mirandola similarly held that “he who lacks reason, then, is not man, but rather a brute to be dragged hither and thither at the beck of the imagination.” And Robert Burton argued in his 1621 Anatomy of Melancholy that “in man it [imagination] is subject and governed by reason, or at least should be; but in brutes it hath no superior, and is ratio brutorum, all the reason they have.”
While humans are aided and guided by reason, the imagination remains a potential source of error and confusion in their souls. The imagination, Pico explains, “is for the most part vain and wandering.” Expressing a nearly identical sentiment to the one grounding Goya’s much later epigraphy, he concludes that “granted that imagination is necessary; nevertheless it is irrational and devoid of correct judgment, unless aided by the guidance of a superior power. Hearkening to this, imagination beatifies man; disobedient to it, imagination dooms him.” Beyond basic perceptual errors and optical illusions, the imagination can produce wonderful and terrifying images. According to Burton, for example, “although this fantasy of ours be subordinate faculty to reason, and should be ruled by it, yet in many men, through inward or outward distemperatuers, defects of organs, which are unapt, or otherwise contaminated, it is likewise unapt, or hindered, and hurt.” In the melancholic man, “this faculty [imagination] is most powerful and strong, and often hurts, producing many monstrous and prodigious things, especially if it be stirred up by some terrible object, presented to it from common sense or memory.” Similarly, Reisch concludes that “sometimes, from the composition of different species of intentions it [imagination] makes monsters, the like of which it has sometimes not seen before.”
We now, then, have a clearer sense of why the imagination, when unguided and unaided by reason, may produce terrifying images and terrible monsters. The imagination is tied to our senses and is responsible for processing various sensual inputs into mental representations. These representations are later stored in the memory and used by our intellect and can be brought back to mind independently of the original thing that caused them. However, the imagination, in itself, is irrational (or, more accurately, pre-rational). Guided by reason, it plays an important role in human epistemology and cognition. Abandoned by it, it may act freely, combining past impressions into absurd and impossible mental representations, including images of monsters and other terrifying creatures.
Having briefly established the reasons behind imagination’s capacity to produce such terrifying images, we may now further inquire into the claim that it is more prone to do so under conditions of solitude. Why, then, is the imagination likelier to be “abandoned” by reason when we are alone? One potential starting point for such an investigation is the state of sleep, which represents a paradigmatic case of the solitary abandonment of reason. “In time of sleep,” explains Burton, “this faculty [imagination] is free, and many times conceives strange, stupend, absurd shapes.” In sleep, he further argues, “the fantasy alone is free, and his commander reason; as appears by those imaginary dreams, which are of divers kinds, natural, divine, demonically, &c.” Therefore, “this we see verified in sleepers, which by reason of humors and concourse of vapors troubling the fantasy, imagine many times absurd and prodigious things.”
Although sleep provides us with the paradigmatic example of the wonderful things created by a free imagination under conditions of solitude, such effects can be found in waking humans as well. Reisch, for example, explains that “the working of this power [imagination] […] are not absent from people awake.” Burton also holds that “the like effects almost are to be seen in such as are awaken; how many chimeras, antics, golden mountains and castles in the air do they build unto themselves?” According to him, fear can stimulate such effects. As he explains, “fear makes our imagination conceive what is list, invites the devil to come to us […] and tyrannizeth over our fantasy more than all other affections, especially in the dark.” And, he concludes, “’tis strange what women and children will conceive unto themselves, if they go over a churchyard in the night, lie, or be alone in a dark room, how they sweat and tremble on a sudden.” Indeed, this sentiment has a long history: it was already expressed by Plato, who was concerned with how “mothers under the influence of such poets terrify their children with harmful tales (μύθους κακῶς), how that there are certain gods whose apparitions haunt the night in the likeness of many strangers from all manner of lands.” And Hobbes, Burton’s contemporary, held that “even they that be perfectly awake, if they be timorous, and superstitious, possessed with fearful tales, and alone in the dark, are subject to the like fancies, and believe they see spirits and dead mens Ghosts walking in Church-yards.”
It is quite clear why the solitude of sleep allows for the imagination to be “abandoned by reason.” During sleep, our senses are inactive. In the absence of new sensual input, the imagination is free to recreate previous sensual impressions without being disturbed by new stimuli. At the same time, it is commonly assumed that reason, too, is inactive during sleep. Unconstraint by the senses or reason, the imagination is entirely free during sleep and thus able to produce impossible and wonderful images. But why should our imagination produce such terrifying monsters when we are alone and awake? Since both our senses and reason are fully active, we should expect our imagination to operate ‘normally’ under these conditions. Yet, as we saw above, philosophers from Plato to Hobbes assumed that when people are “alone in the dark” they may experience very similar things to those found during sleep, despite being fully awake.
To see why solitude can cause this “abandonment of reason” and facilitate the creation of such terrifying monsters by our imagination we should recognize that our imagination is one of the primary causes of subjectivity and difference in opinion among humans. As Pico explains, for example, the imagination is “the source of the shining, the manifold, differences in opinion.” Unlike our senses and reason—which are considered to be rather stable and similar across individuals—our imagination tends to be highly subjective. It is both prone to error and depends on our individual physiology, which means that different individuals are likely to have different “imaginative” experiences.
When we are with other people, we can communicate and share our experiences to distinguish between the “imaginary” and the “real.” We can ask “did you see this?” “Did you hear that?” “Am I imagining, or did [X] just happen?” Through the presence of others, we can stabilize our imagination, “normalize” it in accordance with the experiences of others around us and thus become confident that the things we see, hear, and experience are “real” and not just “in our minds.” We are unable to do so when we are alone. Even though we are perfectly awake, our reason does not always provide a sufficient constraint on our imagination. It still requires the presence of others in order for us to confirm certain things as “real” and rule out other experiences as “imaginary.” The imagination, then, produces “terrible monsters” not only when abandoned by reason. It may do so also when we are abandoned by other people—when we are alone.
I would like to conclude this brief investigation by considering the political implications of these claims about the human imagination. The idea that “imagination abandoned by reason produces impossible monsters” has posed a challenge to political thinkers, from Plato to Hobbes. One of their primary concerns was that humans possessed by such imaginative fears are much likelier to become the targets and victims of vicious and ambitious individuals—particularly religious leaders who seek to gain influence and undermine the civil sovereign. Burton, for example, argues that “for the most part by threats, terrors, and affrights, they [evil priests and other bad men] tyrannize and terrify their distressed souls; knowing that fear alone is the sole and only means to keep men in obedience.” Hobbes expressed this concern even more clearly. According to him, “if this superstitious fear of Spirits were taken away, and with it, Prognostiques from Dreams, false Prophecies, and many other things depending thereon, by which, crafty ambitious persons abuse the simple people, men would be much more fitted than they are for civil Obedience.”
The political problem expressed in these and many other texts can be formulated as follows: the imagination is an unchangeable fact of the human soul. It plays crucial cognitive and epistemological roles and is necessary for nearly all mental activity—from sensual perception to abstract thought. At the same time, the imagination is prone to error and highly subjective. When it is abandoned by reason—for example, when we are asleep or alone in the dark—it can produce wonderful and absurd images and appearances, including terrible and terrifying monsters. These images and appearances, in turn, can be used and manipulated by clever and ambitious individuals who seek to obtain power and control. For Plato, this threat is represented by the poets who, for example, persuade mothers to terrify their children with “bad stories” (μύθους κακῶς) that reinforce false and harmful beliefs. For Hobbes, it is represented by religious figures—and above all prophets—who take advantage of the fears of the common people to undermine the power of the sovereign and establish themselves as an alternative source of authority. This, according to Hobbes, is a major cause of civic unrest and political instability. As he explains in Leviathan, “if men were at liberty, to take for Gods Commandments, their own dreams, and fancies, or the dreams and fancies of private men; scarce two men would agree upon what is Gods Commandment; and yet in respect of them, every man would despise the Commandments of the Common-wealth.”
How did thinkers like Plato and Hobbes solve this problem? While an attempt to fully explore such solutions goes well beyond the scope of this essay, we may briefly sketch its outline here. As we have seen, the imagination is likelier to produce terrible monsters and terrifying images when one is alone. When we are with others, we are better able to “normalize” or “standardize” our imagination so that we may distinguish the “imaginary” from the “real.” If we “normalize” or “standardize” our imagination, and if we could thus remove the subjective fear of solitary individuals, we may be able to make these individuals less vulnerable to the abuses of priests, prophets, and other ambitious persons, and thus secure order and stability. This seems to be what Plato has in mind, for example, when he defines bravery in the ideal city as the “quality that under all conditions will preserve the conviction that things to be feared (τὴν περὶ τῶν δεινῶν δόξαν) are precisely those which and such as the lawgiver inculcated in their education.” And, above all, this idea seems to be motivating the powerful Hobbesian image of the Leviathan. “The great power of his governor,” he explains, “whom I compared to Leviathan, taking that comparison out of the two last verses of the one-and-fortieth of Job; where God, having set forth the great power of Leviathan, calleth him king of the proud. ‘There is nothing,’ saith he, ‘on earth to be compared with him. He is made so as not to be afraid. He seeth every high thing below him; and is king of all the children of pride.’”
Like the Platonic lawgiver, the Hobbesian sovereign will not eliminate individual fear. Instead, both will seek to establish the “correct” objects of fear across individual subjects, thereby “normalizing” and stabilizing the subjects’ imagination, even in the absence of other people around them. Once the lawgiver or sovereign has determined the “incorrect” objects of fear—for example, by ruling out spirits and ghosts as “absurd” and “impossible,” as in the case of the Hobbesian sovereign—their subjects become less prone to the abuses of crafty and ambitious individuals who might take advantage of such imaginative experiences. At the same time, this lawgiver or sovereign will determine the “correct” objects of fear to be shared by their subjects. Thus, in Hobbes’s case, the subjects will be freed of the “erroneous” individual monsters produced by their solitary imagination. But instead, they will now come to share in a collective fear, imagining together one single monster—the mighty and all-powerful Leviathan.
 For example, Plato, Republic, trans. Paul Shorey (Cambridge: Harvard University Press, 1969), 510d–11.
 Aristotle, De Anima, trans. R.D. Hicks (Cambridge: Harvard University Press, 1907), 428a6-20.
 Aristotle, De Motu Animalium, ed. and trans. Martha C. Nussbaum (Princeton: Princeton University Press, 1978), 700b15-20.
 Gregor Reisch, Natural Philosophy Epitomized: A Translation of Books 8-11 of Gregor Reisch’s Philosophical Pearl (1503), trans. Andrew Cunningham and Sachiko Kusukawa (Farnham: Ashgate, 2010), Book X, 2.23.
 Giafrancesco Pico della Mirandola, On the Imagination, trans. Harry Caplan (New Haven: Yale University Press, 1930), 78.
 Robert Burton, The Anatomy of Melancholy (Cambridge: Cambridge University Press, 1905), 212.
 Pico, On the Imagination, 29.
 Ibid., 43.
 Burton, The Anatomy of Melancholy, 336.
 Ibid., 213.
 Reisch, Margarita Philosophica, Book X, 2.23.
 Burton, The Anatomy of Melancholy, 213.
 Ibid., 337.
 Reisch, Margarita Philosophica, Book X, 2.23.
 Burton, The Anatomy of Melancholy, 337.
 Ibid., 348–49.
 Plato, Republic, 380d.
 Thomas Hobbes, Leviathan, ed. Noel Malcolm (Oxford: Clarendon Press, 2012), 2, 78.
 Pico, On the Imagination, 47.
 As we saw, Burton held that “through inward or outward distemperatuers, defects of organs, which are unapt, or otherwise contaminated, it [imagination] is likewise unapt, or hindered, and hurt.” Burton, The Anatomy of Melancholy, 336.
 Indeed, Hobbes seems to reflect a similar sentiment in his discussion of language. Words, according to him, produce “signs” and “marks,” which can be used to stabilize the products of our imagination and allow for communication across different individuals. For example, Thomas Hobbes, The Elements of Law: Natural and Politic, ed. J.C.A. Gaskin (Oxford: Oxford University Press, 2008), 35.
 Burton, The Anatomy of Melancholy, 385.
 Hobbes, Leviathan, 2, 34.
 Plato, Republic, 380d.
 Hobbes, Leviathan, 26, 446.
 Plato, Republic, 429b.
 Hobbes, Leviathan, 28, 496.