What is the definition of "Genius" in An Essay on Criticism? Not the modern day usage of the word.
English poet Alexander Pope (1688-1744) published an Essay on Criticism anonymously in 1711. It's one of the first examples of a Poetic Essay, and in it he explores the arguments if poetry itself should follow the "natural" rules of Nature, or should adhere to the "artificial" forms of the Ancients. A poet possessing poetic "genius" would be able to write poetry that transcends the normal rules; however, only a critical "genius" would be able to appreciate the work and laud the poet.
Interestingly, the word "genius" comes from the same root as "genii" and originally meant a spirit attendant upon a person. By the 1600's that gave way to mean a person's characteristic disposition, and by Pope's time, to mean a sense of a person's natural ability. The concept of a genius possessing an exceptional ability came after Pope's time.