ROCKLAND – The violas play it at normal speed, the violins go twice as fast, and the basses play twice as slowly.

The piece is “Festina Lente,” literally fast-slow, and Arvo Part’s three-part canon will be a highlight of a Portland Symphony Orchestra concert, “Sacred and Profane,” at 7:30 p.m. Jan. 20, at Rockland District High School.

The concert, an entry in the symphony’s Mozart and More concert series of chamber music, will be repeated at 2:30 p.m. Jan. 21, at Merrill Auditorium in Portland.

Soloist for the concert will be harpist Jara Goodrich, who also plays with the Bangor Symphony Orchestra, the Portland Opera Repertory Theatre, Portland Ballet and the Maine Music Society.

The Limerick resident will play Debussy’s “Danses Sacree et Profane,” a two-part work featuring harp and string orchestra – one facet intended to be ethereal and atmospheric, the other a rhythmic waltz.

“I enjoy playing chamber music because the harp has more of an opportunity to speak,” Goodrich said. “I especially enjoy Debussy music,” his impressionistic style is very well-suited to the harp.”

Another highlight of the concerts will be Jeremy Beck’s recent work, “Sparks, and Flame (Ash).” Beck will be on hand for the Portland concert, and will give a talk at 1:15 p.m. Jan. 21, in Merrill Auditorium.

He composed the piece for Rebecca Burkhardt and the Northern Iowa Symphony Orchestra before its 1997 tour of Russia.

The last performance of each concert will be Mozart’s “Serenade No. 9 – Posthorn,” the last of the composer’s Salzburg Serenades.

Tickets for the Rockland concert are $22 and $15, with discounts for senior citizens, groups and students. They are available at Harbor Audio-Video in Camden and The Reading Corner, Rockland.

Portland tickets are $28, $23 and $17, and similar discounts are available.

Tickets also may be obtained by phone from PortTix at 842-0800, or on the Internet through www.portlandsymphony.com.