"In this monograph the author describes the basis and derivation of the macroscopic or phenomenological theory of the elastic, dielectric and thermal properties of crystals as applied in the field of ferroelectricity. Most of the results and ideas described are scattered through the literature of this subject and this book presents them together with their physical background in one reference. The discussion is restricted to the theory required to describe the properties of homogeneous specimens subject to low frequency fields." Got it?