An object of art could be beautiful yet it could not possess greatness. His Pleasures of the Imagination, as well as Mark Akenside's Pleasures of the Imagination of 1744 and Edward Young's poem Night Thoughts of 1745 are generally considered the starting points for Edmund Burke's analysis of sublimity. Edmund Burke developed his conception of sublimity in A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful of 1756. Burke was the first philosopher to argue that sublimity and beauty are mutually exclusive. The dichotomy that Burke articulated is not as simple as Dennis' opposition, and is antithetical in the same degree as light and darkness. Light may accentuate beauty, but either great light or darkness, i. e., the absence of light, is sublime to the extent that it can annihilate vision of the object in question. What is "dark, uncertain, and confused" moves the imagination to awe and a degree of horror. While the relationship of sublimity and beauty is one of mutual exclusivity, either can provide pleasure. Sublimity may evoke horror, but knowledge that the perception is a fiction is pleasureful. Burke's concept of sublimity was an antithetical contrast to the classical conception of the aesthetic quality of beauty being the pleasurable experience that Plato described in several of his dialogues, e. g. Philebus, Ion, Hippias Major, and Symposium, and suggested that ugliness is an aesthetic quality in its capacity to instill intense emotions, ultimately providing pleasure. For Aristotle, the function of artistic forms was to instill pleasure, and he first pondered the problem that an object of art representing ugliness produces "pain." Aristotle's detailed analysis of this problem involved his study of tragic literature and its paradoxical nature as both shocking and having poetic value. The classical notion of ugliness prior to Edmund Burke, most notably described in the works of Saint Augustine of Hippo, denoted it as the absence of form and therefore as a degree of non-existence. For St. Augustine, beauty is the result of the benevolence and goodness of God in His creation, and as a category it had no opposite. Because ugliness lacks any attributive value, it is formless due to the absence of beauty. Burke's treatise is also notable for focusing on the physiological effects of sublimity, in particular the dual emotional quality of fear and attraction that other authors noted. Burke described the sensation attributed to sublimity