Symmetry of Permittivity Matrix in Anisotropic Materials

[Blukstak]

I can't seem to demonstrate that in anisotropic materials the permittivity matrix is symmetric, apparently this is done with the poyinting vector...

I really need to understand it thanks...

 

[Meir Achuz]

There are arguments for the symmetry of epsilon, but they tend to be circular.
This is because electromagnetic energy can ony be defined if epsilon is symmetric.