From Preface: The title Middle Class is here applied to the equestrian order, which is described by the Elder Pliny as a tertium corpus which inserted itself between the senatorial class and the mass of the Roman people. I have also used to allude to this class the Latin word Equites. This usage should be distinguished from that of equites (in italics) which means "calvalry". I have avoided the term "knights", commonly used in this connection, because it seems to me inappropriate.