We are misled when we believe that our ideas represent or mirror nature, because that sets us outside nature as mere observers. The tree does not represent the fish, though both use light and water. The point is rather that our thoughts and ideas are nature, just as much as waves on the ocean and clouds in the sky. The mind grows thoughts as the field grows grass. If I think about thoughts, as if there were some "I," some thinker watching them from outside, there arises the infinite regression of thinking about thinking, etc., because this "I" is itself a thought, and thoughts, like trees, grow of themselves. In solitude it is easier for thoughts to leave themselves alone. It is, thus, a mistake to try to get rid of thoughts, for who will push them out? But when thoughts leave themselves alone the mind clears up.