There are a variety of philosophies, artistic processes, and theatrical approaches to creating plays and drama. Some are connected to political or spiritual ideologies, and some are based on purely "artistic" concerns. Some processes focus on a story, some on theatre as event, and some on theatre as catalyst for social change. According to Aristotle's seminal theatrical critique Poetics, there are six elements necessary for theatre: Plot, Character, Idea, Language, Song, and Spectacle. The 17th century Spanish writer Lope de Vega wrote that for theatre one needs "three boards, two actors, and one passion". Others notable for their contribution to theatrical philosophy are Konstantin Stanislavski, Antonin Artaud, Bertolt Brecht, Orson Welles, Peter Brook, and Jerzy Grotowski. Some theatre theorists argue that actors should study all of the commonly-taught acting methods to perfect their craft (though many others disagree), such as the Meisner, Stanislavsky, Strasberg, and Hagen acting methods. Theater, overall, encompasses people, ideas, and the works of art that result from their collaboration.