Traditional pedagogy had to accommodate it. This translates to teacher, humility, and discipline. The guru , or teacher is the most important prerequisite in traditional musical pedagogy. This is considered the highest form of knowledge. This also reflects the divine origins of the artform.
Classical music is said to be a worship that involves both the listener and the artist alike.
Sadhana is necessary at two levels. However, from a simple pedagogic standpoint, the music is so incredibly difficult that if the student does not devote countless hours of practice spread over many years, the student certainly will not be able to master the music. Any art must deal with the topic of aesthetics. The Indian tradition has much to say on this point as well. The ancient scriptures describe nine fundamental emotions from which all complex emotions may be produced.