A post by Evelyn Lamb on the Scientific American blog. A quote:

Thurston embraced efforts to make mathematics more accessible and enjoyable for students and the general public, especially in later years. In a 1994 article for the Bulletin of the American Mathematical Society, he wrote that the fundamental question for mathematicians should not be, “How do mathematicians prove theorems?” but, “How do mathematicians advance human understanding of mathematics?” He believed that this human understanding was what gave mathematics not only its utility but its beauty, and that mathematicians needed to improve their ability to communicate mathematical

ideasrather than just the details of formal proofs.He worked on projects to increase public understanding of mathematics and saw the mathematical sides of art and design. He co-developed a course called “Geometry and the Imagination” designed to introduce deep geometric concepts to people who did not necessarily have an advanced background in math.