Pacific Baroque Orchestra’s Christmas show is called Es ist ein Ros entsprungen, and in case you don’t have a rudimentary knowledge of German, that means “A Spotless Rose”—the name of a well-known traditional Christmas tune in the 16th and 17th centuries. That title captures the antique mood of a concert devoted to some of the baroque period’s sparkling holiday treasures, including a few of Antonini Vivaldi’s shimmering motets. Arcangelo Corelli, George Frederick Handel, and other masters make it onto the program, with help from guest soprano and acclaimed early-music specialist Suzie LeBlanc. Es ist ein Ros happens Saturday (December 7) at Pyatt Hall and again the next afternoon at Langley Community Music School.