Klaus Mertens and consistency, Klaus Mertens sang in every piece that required a bass soloist, 190 in all." He is also involved in the project Dieterich Buxtehude – Opera Omnia of the same ensemble to record the complete works of Dieterich Buxtehude, begun in 2005. As a singer of lieder, he has interpreted songs of Claudio Monteverdi, Antonio Caldara, Wolfgang Amadeus Mozart and Franz Schubert among others. He has performed the title roles of the romantic oratorios "Elijah" and "St. Paul" by Mendelssohn and, as music of the 20th century, Paul Hindemith's "Requiem" and Igor Stravinsky's "Oedipus rex". In the classical repertory
Elijah analogy for Perun, the supreme Slavic god of storms, thunder and lightning bolts. In many Slavic countries Elijah is known as Elijah the Thunderer ("Ilija Gromovnik"), who drives the heavens in a chariot and administers rain and snow, thus actually taking the place of Perun in popular beliefs. Perun is also sometimes conflated with the legendary hero Elijah of Murom. The feast of St. Elias is known as "Ilinden" in South Slavic, and was chosen as the day of the Ilinden-Preobrazhenie Uprising in 1903; it is now the holiday of Republic Day in the Republic of Macedonia. In Estonian folklore