  who emphasized the role of gauge invariance as a symmetry  principle from which electromagnetism can be derived. It took  several decades until the importance of this symmetry  principle—in its generalized form to non-Abelian gauge groups  developed by Yang, Mills, and others—also became fruitful for a description of the weak and strong interactions. The mathematics of  the non-Abelian generalization of Weyl’s 1929 paper would have been  an easy task for a mathematician of his rank, but at the time there  was no motivation for this from the physics side.