Symmetries of Feynman Symmetries (SFI) is a general theory for the evaluation of Feynman diagrams, which is related to both IBP and DE. For any given diagram topology it defines a set of partial differential equations in terms of the most general parameters - masses and kinematical invariants. The equation system is associated with a group G whose orbits foliate the parameter space. The general integral is shown to reduce to its value at conveniently chosen parameters on the same G-orbit plus a line integral over simpler diagrams - diagrams with one propagator contracted. Additional aspects of the theory and some applications will be discussed.