A simple three-dimensional model is proposed which is based on characteristic surface the second rank tensor - three-axial ellipsoid. It is shown that due to symmetry of molecular oscillations in a liquid crystal (LC) it is possible to calculate its basic anisotropic characteristics by using oscillation magnitudes in isotropic state as a reference. It has been found that in ellipsoid sections there are directions, corresponding to an angle Theta(0) = arccos root 1/3 relative to major semiaxes of ellipsoid sections, with respect to which thermal properties of anisotropic physical quantities remain invariant. It is shown that ordinary wave refractive index no has different values for light beams propagating along and normal to the oriented nematic director.