A lesser known philosopher is Eduard von Hartmann, whose goal was to reconcile Hegel and Schopenhauer's philosophies, believing "a will which does not will something is not." He arrived at the idea that the world was driven by an Unconscious nature, to which both will and idea were opposite poles; his main work was titled Philosophy of the Unconscious, and it was the first book that really popularized the idea of the 'unconscious' in the 19th century, far ahead of Freud. When his book was published he became popular overnight.
This type of drive you see in the 19th century, btw, to make sense of the truths of different philosophical systematizations, was promoted by a philosopher I've mentioned before, Victor Cousin. He's known for a school called Eclecticism, and argued that different systems of philosophy came about because people were defending some fact at its base, and that even though they all had truth they all have defects. Cousin believed in the idea of theodicia, the idea that all belief systems intersect in some way. He also is the one who coined the principle 'art for art's sake' (which is actually from a longer quote, "art for art's sake, and philosophy for philosophy's sake"). For philosophy, he believed that it was necessary to understand what was implied in language. Otherwise you would get caught in constructions, as he argued the German philosophers did. For instance we talk about 'free will' because the concept of 'freedom' is implicit in the concept of 'willing.' (He also argued at another point, arguing against mysticism, that if theres one thing we can say about God is that he has 'being', which is implied by using the word. He used the word God synonymous with the idea of a 'first principle', following Platonic thought.) He promoted the idea that philosophy was rooted in study of the mind and its concepts, or psychology, and that it always needed to learn from its history. In fact he founded the first departments of psychology that existed, and wrote books devoted to it. He picked up the term from Thomas Reid, a contemporary of Hume and a critic of him, who started the Common Sense school (believing all truth is found in common sense). The word hadn't been used since the ancient greeks. Later psychologists that emerged hated Cousin though because he grounded his psychology in metaphysics and not empirical study. But his thinking was very influential not only on psychology but sociology.
