Abstract: This talk by Cumrun Vafa reviews some of the lessons string theory has taught us about the fundamental laws of nature. Duality symmetries discovered in string theory play a key role. Biosketch: Cumrun Vafa is a theoretical physicist whose primary area of research is string theory. He is the Donner Professor of Science in the Department of Physics at Harvard University. He won ICTP’s Dirac Medal in 2008 along with Juan Maldacena and Joseph Polchinski for fundamental contributions to superstring theory. In 2017, he received the Breakthrough Prize in Fundamental Physics, together with Polchinski and Andrew Strominger, for transformative advances in quantum field theory, string theory, and quantum gravity. Vafa is a member of ICTP’s Scientific Council.