Quite simply put - the Sicilian Defense is the most popular and most complex of opening systems in chess. It has been the favorite of top players throughout modern times. There are a number of systems and variations to choose from such as the Scheveningen, Dragon, Najdorf, Boleslavsky, Kan, etc. There are also a number of sharp, complex, theoretical systems and that is why it is aptly named "The Sicilian Jungle." IM Dr. Danny Kopec's addresses the problem of trying to simplify the complexities of the Sicilian Defense from the perspective of STRUCTURE - that is, sound structures for Black, particularly for the endgame. Dr. Kopec uses a unique method which he calls "Mastery Lessons" to guide the learner towards pawn structures and piece configurations which have been demonstrated to lead to success in certain Sicilian variations. This approach, developing "heuristic packets", helped to achieve master level play in his work with computer chess programs.