  Skew-symmetric forms possess unique capabilities. The properties of closed
exterior and dual forms, namely, invariance, covariance, conjugacy and duality,
either explicitly or implicitly appear in all invariant mathematical
formalisms. This enables one to see an internal connection between various
branches of mathematics. However, the theory of closed exterior forms cannot be
completed without an answer to a question of how the closed exterior forms
emerge. In the present paper we discus essentially new skew-symmetric forms,
which generate closed exterior forms. Such skew-symmetric forms, which are
evolutionary ones, are derived from differential equations, and, in contrast to
exterior forms, they are defined on nonintegrable manifolds.
