Complex sentence: The hyperbolic plane is a plane where every point is a saddle point, unfortunedly by Hilbert's theorem it is not possible to create a complete hyperbolic plane (a complete regular surface of constant negative Gaussian curvature) in Euclidean space.
Split into simpler sentences: The hyperbolic plane is a plane where every point is a saddle point. Unfortunately, by Hilbert's theorem it is not possible to create a complete hyperbolic plane (a complete regular surface of constant negative Gaussian curvature) within Euclidean space.