What are some characteristics of the "sublime"?

The sublime is a guiding principle of both Romanticism and its sister movement gothic literature. It draws largely from Edmund Burke's 1757 work, A Philosophical Enquiry into the Origin of Our Ideas of the Sublime and Beautiful. Burke's sublime is drawn from passion and "astonishment," a state in which "the mind is so entirely filled with its object, that it cannot entertain any other." Astonishment, then, according to Burke, is what causes something to become, to us, a sublime object which pushes everything else out of our consciousness. Violent, or forceful, emotions are the key to what makes something sublime. Burke also identifies "terror" as, in fact, "the ruling principle" of the sublime, which gives some indication of why the sublime is as much a commonality in gothic literature as in Romanticism. The sublime can be reached as much—and, indeed, perhaps more—through the sort of terror which overcomes a person entirely, as through astonished awe at the beauty of nature.
The sublime was adapted by the Romantics mainly in terms of its emphasis upon strong emotion. For Wordsworth and other Romantic poets, the sublime in nature represented something so beautiful or awe-inspiring that it provoked strong emotions and therefore became sublime. It is notable, however, that Burke makes a distinction between the sublime and the beautiful. While something can be sublimely beautiful, things may also be sublimely terrifying. Burke also makes a clear distinction between the effects of the sublime—which are overwhelming and "tighten" the fibers of the body—and those of the beautiful, which should relax the beholder to a supreme degree.
For Burke, something is sublime or beautiful not because of what it is in itself, but because of the strength of its effect on the beholder. As such, the idea of the sublime is not objective but entirely subjective.