>>41002890
>The discovery of duality symmetries in string theory has led to spectacular progress in our understanding of non-perturbative aspects of the theory. However, we still do not have a deep understanding of the meaning of these symmetries. Indeed, we find ourselves in the strange situation that the quantum corrected physics has more symmetries than the classical strings had any right to expect!
--A Mysterious Duality, Amer Iqbal, Andrew Neitzke, Cumrun Vafa