### Abstract

Dedicated to the many bright young theoretical physicists that failed to escape the fate of having to work in institutions like banks. Preface New? In what sense? Surely I am not the only person who, after extensively justifying why certain mathematical structures naturally arise in physics, gets questions like: “this is all nice maths but what’s the physics? ” Meanwhile I figured out what this truly means: “I don’t see any differential equations! ” Okay, this is indeed a bit overstated. Nowadays any mathematical argument involving groups, when these are moreover referred to as ‘symmetry groups’, stands a serious chance of being eligible for carrying the label ‘physics’. But it hasn’t always been like this. John Slater (cf. the Slater determinant in quantum chemistry) referred to the use of group theory in quantum physics by Weyl, Wigner et al. as der Gruppenpest, what translates as the ‘plague of groups’. Even in 1975 he wrote [14]: “As soon as [my] paper became known, it was obvious that a great many other physicists were as ‘disgusted ’ as I had been with the group-theoretical approach to the problem. As I heard later, there were remarks made such as ‘Slater has slain the Gruppenpest’. I believe that no other