Based on a conception in which a musical composition determines aesthetic-normative properties, a distinction is drawn between two notions of performance: the "autonomous", in which a performance is regarded as a musical work on its own, and the "intentionalistic", in which it is regarded as essentially of a particular work. An ideal performance, under the intentionalistic conception, is one that realizes all the aesthetic-normative properties of the work. A great performance is characterized as one that reveals important aesthetic-normative properties of the work that are rather concealed, such that we would find it difficult to conceive of them independently of the performance. Various features of the difference between these notions of ideal and great performance are discussed. Unlike an ideal performance, a great performance, is by its very nature, an actual performance, whose very presence reveals to us important properties of the work. This is claimed to explain various intuitive features of what we regard as great performances. However, it is also claimed that by the above characterization the notion of great performance point to the limits of the intentionalistic conception of performance.