An oratorio is a large musical composition incluing an orchestra, a choir, and soloists. The oratorio was somewhat modeled after the opera. Their similarities include the use of a choir, soloists, an ensemble, various distinguishable characters, and arias. However, opera is musical theatre, while oratorio is strictly a concert piece, though they are sometimes staged as operas. There is little or no interaction between the characters, no props or elaborate costumes. The most important difference is their subject matter. Opera tends to deal with history and mythology, including age-old devices of romance, deception, and murder. There are many exceptions, including Saint Saens' opera, Samson et Dalila, Schoenberg's Moses and Aaron and others. Additionally, there are operas that deal with religious movements such as Meyerbeers Les Huguenots. The plot of an oratorio is often minimal and deals strictly with sacred subjects, making this form of entertainment acceptable and appropriate for performance in the church. Protestant composers took their stories from the Bible, while Catholic composers looked to the lives of saints. Oratorios became extremely popular in early 17th century Italy partly because of the success of the opera and the Church's prohibition of spectacles during Lent. Oratorios became the main option of musica during that period for opera buffs.