It is a pity for all of us that Dimitri Mihalas was unable to come to Sydney, and I wish, in the first place, to thank him for suggesting this discussion, devoted to a prospective study of our research field. There falls to me the task of trying to sketch what might be the axis of progress in stellar atmosphere theory. This subject is preeminently one which belongs to D. Mihalas; I am afraid that we are going to miss him now more than ever. Furthermore, I feel myself in a bad position for talking on such a large subject, in front of specialists, while I know so little on it. However, I have accepted the task, at the request of the President of Commission 36, with the goal of giving some physical considerations that may initiate reflections and discussions.

I am not going, in principle, to give a set of topics whose study should be desirable, or possible, arranged according to the internal logic of a specialist of stellar atmospheres, neither shall I look for bibliographical signs allowing the prediction of active zones or flares in our next cycle of activity!