19th Century Romanticism was greatly dominated by 'German Idealism'. Influenced by the almighty power of the Prussian State, it produced such philosophers as Immanuel Kant who declared that "not everything can be known" - the idea that certain knowledge of the world is beyond our understanding.
His philosophy went on to influence the likes of Hegel, Byron and Schopenhauer at a time when British Empiricism was thriving.
