"in his 5th chapter of the Bathos"
Alexander Pope
Public DomainAlexander Pope - Credit: Jean-Baptiste van Loo c.1742

Bathos is an abrupt transition in style from the exalted to the commonplace, producing a ludicrous effect. The term was introduced by Alexander Pope in his essay Peri Bathous, Or the Art of Sinking in Poetry (1727).  While contemporary writers had detailed the ways in which poetry could ascend or be awe-inspiring, Pope offered a long discussion of how authors might ‘sink’ in poetry.  The work described various methods for writing poorly, but the one that is best remembered is the act of combining very serious matters with very trivial ones i.e. bathos. 

Pope offered as an example Master of a Show in Smithfield, who wrote in large Letters, over the Picture of his Elephant:

"This is the greatest Elephant in the World, except Himself."