Our Symposium has truly been held in the spirit of IAU Commission 33. This Commission has traditionally provided the opportunity for optical and radio astronomers to meet with theorists interested in the dynamics of stellar systems. Our good relations with Commission 34 assure us that in our deliberations we shall not lose sight of the physical implications of our theoretical and observational developments. The past and present Presidents of Commission 33 are proud of the fact that they – and their Organizing Committees – took the initiative for holding this Symposium in Basel. We need not hide the fact that the plan to go to Basel came because many of us wished to honor Wilhelm Becker and his associates for the beautiful and basic researches they have done relating to the spiral structure of our Galaxy.