The sublime is a very useful concept for understanding what makes something gothic. And it can be usefully compared to the uncanny.
The first century Greek writer Longinus defined the sublime as language that “transports” the reader, that “shatters the reader’s composure,” that dominates him or her. The source of the sublime can loftiness of thought and strong and inspired passion.
Edmund Burke wrote Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful (1757) in which he stated that the sublime consists of those things that are “terrible” and that “excite the ideas of pain, and danger” provided that the reader is safe from danger and can thus experience the painful terror as a “delightful horror.” Burke thought certain features such as obscurity, immense power, and vastness of space could provoke this feeling.
Immanuel Kant thought the sublime could be divided into two categories in his Critique of Judgement (1790). The mathematical sublime encompasses the sublime of magnitude—of vastness in size or limitlessness or infinitude in number. The dynamic sublime encompasses the objects conducive to terror at our seeming helplessness before the overwhelming power of nature, provided that the terror is rendered pleasurable by the safety of observer.
(from A Glossary of Literary Terms, 10th ed.)