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) $\times$ SO(16) is discussed from this perspective, as well as an ansatz to construct yet further versions with SO(1,1) $\times$ SO(16)$^\infty$ and possibly even SO(1,1)$_+$ $\times$ ISO(16)$^\infty$ 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 $SU(\infty)$ Yang Mills theory. 
Hermann Nicolai (AEI Potsdam)