Welcome to this month’s crossword, constructed by Irene Cesa, a retired chemist from Wheaton, Illinois, and George Barany, professor emeritus of chemistry at the University of Minnesota Twin Cities. They thank Mark Cesa, Charles M. Deber, Michael Hanko, Paul Rossi, and Peggy Schott for test solving and Marcia Brott for editorial suggestions. Metaphors can help us see concepts, whether old or new, in a different light.