Abstract
We try to show the necessity of accepting the fundamental continuity hypothesis, which implies introduction of such new notions as integral parameters of a medium and their densities. We also discuss a configuration of a body and its deformation as well as methods of its description. The concepts of the Lagrangian and Euler coordinates are considered.
Keywords: Causality principle, Conservation law, Continuity hypothesis, Continuum, Current configuration, Deformation, Euler coordinates, Integral parameter, Knudsen number, Lagrangian coordinates, Local parameter (density), Reference configuration.