What is "metahistory"

Metahistory: The Historical Imagination in Nineteenth-century Europe is a work of historiography by Hayden White first published in 1973.

On the second page of his Introduction White stated: The theoretical framework is outlined in the first 50 pages of the book, which consider in detail eight major figures of 19th-century history and the philosophy of history. The larger context of historiography and writing in general is also considered. White's approach uses systematically a fourfold structural schema with two terms mediating between a pair of opposites.