There is a long history of debate over what opera is. Since it's more or less formal beginning in the sixteenth century as a reconstruction of ancient drama, opera as an art form has been controversial. The received understanding--emphasized by the genre's founders and in periodic efforts at reforming the standards of composition and production--is that opera is musical drama. Others view opera as music; while others consider it as revelation. These three conceptions of opera are not meant to include all of the conceptions that play a role in debates about the meaning and value of opera. At the same time, they serve as the most visible and, for many, the most plausible conceptions. However, the author thinks that each conception is problematic. In this article, the author suggests that opera performances have the potential to be truly extraordinary aesthetic experiences. He proposes to follow a suggestion by Benjamin Britten. "Music," Britten says, "does not exist in a vacuum, it does not exist until it is performed, and performance impose(s) conditions." The central condition is that it is an experience that occurs only in what Britten calls the "holy triangle of composer, performer, and listener." (Contains 30 notes.)