Art of representing a character on a stage or before a camera by means of movement, gesture, and intonation. Acting in the Western tradition originated in Greece in the 6th century BC; the tragedian Thespis is traditionally regarded as founder of the profession. Aristotle defined acting as the right management of the voice to express various emotions and declared it a natural gift that he doubted could be taught. Acting declined as an art in the Middle Ages, when Christian liturgical drama was performed by craft guilds and amateurs. Modern professional acting emerged in the 16th century with Italy's commedia dell'arte troupes. It flourished during the era of William Shakespeare. Not until the 18th century, however, was acting considered a profession to be taken seriously, through the efforts in England of the actor-manager David Garrick and the talents of actors such as Sarah Siddons, Edmund Kean, and Henry Irving. Modern acting styles have been influenced by Konstantin Stanislavsky's emphasis on the actor's identification with his role and by Bertolt Brecht's insistence on the objectivity and discipline of the actor. The Stanislavsky method was adopted in the U.S. by Lee Strasberg and Stella Adler (1901–92) and is the basis of most contemporary training, which features the cultivation of emotional and sense memory, physical and vocal training, and improvisation.