Mount St. Mary’s Seminary & School of Theology will celebrate Solemn Passiontide Vespers at 7 p.m., preceded by an organ recital at 6:30 p.m. in the Chapel of St. Gregory the Great. The program will be sung by the Latin Schola — the seminary’s principal choir — comprising late medieval polyphony and plainchant drawn from several different rites: Roman, Ambrosian, Dominican, Mozarabic, and Sarum. The pre-vespers organ recital will be performed by Michael Dailey, Director of Music at Our Lord…