 Leaving his mother’s apartment in 1814 where he had been residing briefly, Schopenhauer moved to Dresden, where he lived until 1818. There he developed ideas from The Fourfold Root into his most famous book, The World as Will and Representation, that was completed in March of 1818 and published in December of that same year (with the date, 1819). In sympathy with Goethe’s theory of color, he also wrote On Vision and Colors (1816) during this time. In Dresden, Schopenhauer developed an acquaintance with the philosopher and freemason, Karl Christian Friedrich Krause (1781–1832), who had also been one of Fichte’s students in Berlin, whose own panentheistic views appear to have been influential. Panentheism (i.e., all-in-God), as opposed to pantheism (i.e., all-is-God), is the view that what we can comprehend and imagine to be the universe is an aspect of God, but that the being of God is in excess of this, and is neither identical with, nor exhausted by, the universe we can imagine and comprehend. As we will see below, Schopenhauer sometimes characterized the thing-in-itself in a way reminiscent of panentheism.