It is Example 4.5 in Griffiths intro to Electrodynamics. A metal sphere of radius a carries a charge Q. It is surrounded, out to radius b, by linear dielectric material of permittivity epsilon .... He goes on to say that E = P = D = 0 inside the sphere. I understand that D = 0 inside, but why is E = 0? Is the polarization of the dielectric pulling all of the charge inside the sphere to the surface? I really don't understand :(.