The previous editions of this book have never looked very much like their predecessors, and this fourth edition is no exception. Due to the accumulation of new findings during the seven years that has passed since the previous update, practically all chapters are either completely rewritten or are totally new. We (the editors) and the contributors have strived to reach a proper balance between the well-established “eternal truths” and the novel and even controversial findings. While keeping the format of individual chapters as reviews, a certain compromise between comprehensiveness and readability has been aimed at in order to avoid an excessive length and too massive a size.
