On M-theory

This contribution gives a personal view on recent attempts to find a unified framework for non-perturbative string theories, with special emphasis on the hidden symmetries of supergravity and their possible role in this endeavor. A reformulation of d = 11 supergravity with enlarged tangent space symmetry SO(1, 2) x SO(16) is discussed from this perspective, as well as an ansatz 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 is suggested that upon "third quantization", dimensionally reduced maximal supergravity may have an equally important role to play in this unification as the dimensionally reduced maximally supersymmetric SU(infinity) Yang Mills theory.