Quantum Inverse Scattering Method is largely due to the works of L.D. Faddeev and his school. We illustrate some of its ideas with the special emphasis on the role of underlying hidden symmetry. As an example we discuss the generalized Gaudin model. Recent results of B. Feigin, E. Frenkel and N. Reshetikhin provide a link between the original ideas of QISM and the representation theory of affine Lie algebras (or their $q$-deformations) at the critical value of central charge.