G.E. Moore is best known as a neo-realist and an adversary of hegelianism and idealism in philosophy at the beginning of the twentieth century. He is also a great philosopher of language and one of the founding fathers of analytical philosophy with B. Russell, who was his friend in Cambridge. Just like the idealists, he thinks that there are objects which are neither in space nor in time and have no reference in the empirical world. “Good” is an object of that kind: it exists but is not, and it cannot be defined. It is unanalysable. A sign can have meaning and no reference. G.E. Moore, just like Frege, but with different methods, thinks that it is necessary to oppose meaning and reference. Like many other philosophers at the beginning of the twentieth century, he fights for the idea that the world is independent of thought, and that it is the purpose of philosophy to describe such a universe.