On M-theory

This contribution gives a personal view on recent attempts to find a unifie d framework for non-perturbative string theories, with special emphasis on the hidden symmetries of supergravity and their possible role in this endea vor. A reformulation of d = 11 supergravity with enlarged tangent space sym metry SO(1, 2) x SO(16) is discussed from this perspective, as well as an a nsatz to construct yet further versions with SO(1, 1)x SO(16)(infinity) and possibly even SO(1, 1)(+) x ISO(16)(infinity) tangent space symmetry. It i s suggested that upon "third quantization", dimensionally reduced maximal s upergravity may have an equally important role to play in this unification as the dimensionally reduced maximally supersymmetric SU(infinity) Yang Mil ls theory.