In the chapter on Neo-Realism in the second part of this book, we observed that early twentieth century British philosophy is characterized by a turn from metaphysics to science, and from idealism to realism. It was noted that in the work of Moore and Russell this turn is accompanied by an approach to philosophy which emphasizes the analysis of language. Russell's background in logic and mathematics led him to focus on becoming as clear and precise as possible concerning the language in which metaphysical problems are discussed. Moore did not share Russell's background in mathematics and logic and was more concerned with common sense and ordinary language, but he shared with Russell the goals of clarity and precision in the use of language. Moore and Russell continued to be interested in many traditional philosophical problems, but their approach to these problems through a careful analysis of language helped stimulate a more radical development in the work of Russell's brilliant student, Ludwig Wittgenstein. Wittgenstein argued in his early work, Tractatus Logico-Philosophicus, that meaningful discourse is empirical in nature and that metaphysical questions fail to meet this standard of meaningfulness. What we cannot speak of meaningfully, he concludes, we must pass over in silence.