Miloš Kössler (1884-1961), Professor in the Charles University, was not only a renowned specialist in theory of analytic functions and number theory but primarily excellent teacher. He served as the secretary of the Royal Czech Society of Sciences and in 1953 he was elected one of the first Corresponding Members of the Czechoslovak Academy of Sciences. He worked in the Board of the Union of Czechoslovak Mathematicians and Physicists from 1917 to 1947 contributing to its flowering.