Abstract :
My teacher, the person who taught me the profession of scientist, was Mikhail Alexandrovich Leontovich. His teacher was Leonid Isaakovich Mandelstam. When studying at the Moscow University, I attended his physical seminar several times. Usually, “entire physical Moscow” met there. For the students this seminar was quite complicated. In fact, I understood very little from the reports, but resuming words of L.I. were, as a rule, understandable. Now I know that if the speaker understands what he made, then he can explain the essence of his work in a form clear to “almost anyone”. The technique can be complicated but the logic is always simple.
