Russian researchers have been looking at phenomena of linked mechanical and electromagnetical properties; their goal has been to find anomalies in electromagnetic properties (primarily currents and radiation) induced by mechanical anomalies (propagating seismic waves). In mathematical physics the notion of generalized forces, coordinates, and work functions is a powerful and mathematically elegant tool to describe the dynamic state of a physical system. Rigorous mathematical treatments given in Lanczos (1970) and Landau et al (1984) show that the state of a physical system can be described by complete sets of dependent and independent generalized variables. These variables usually do not have geometrical euclidian meaning; rather they describe the system in an abstract space called phase space. The equations describing the evolution of the system take on canonical form in these coordinates. Consequently mathematical concepts like Lagrange's variational principle or Hamilton's principle also take canonical form. In this paper I combine the ideas of elastic stresses, electric field strengths, and entropy into a generalized stress theory (the stresses being dependent variables) in order to describe the dynamic state of a solid body. Such generalized stress can be linearly related to generalized displacement, which combines elastic strains, electric displacement, and temperature. This concept implicitly incorporates important thermodynamic principles such as Onsager's principle. It is a macroscopic description of rock properties and consequently allows us to assign some average properties to the medium. I omit the consideration of porous media, since it exceeds the scope of linear theory.