Resolving the Algol Paradox and Kopal’s Classification of Close Binaries with Evolutionary Implications

The Algol paradox posed a serious challenge to the theory of evolution of close binaries. We indicate that it has been resolved by the collective efforts of a whole generation of astronomers rather than by anyone’s individual ingenious accomplishment. We discuss the role of illuminating ideas put forward by Zdeněk Kopal in solving the Algol paradox.