You can have two individuals, with similar musical technical ability, play the same exact notes on a guitar and receive completely different reaction from the audience. You can also have musicians who train day in and day out and become extremely good at technically manipulating their instrument but when you hear them play, they hardly evoke any emotional reaction in the audience. On the other hand, you have the other kind of musicians, who may either be technically good or not, but their delivery always triggers a palpable emotional reaction in their audience. So what is the element that makes the difference?
Maybe we can begin to answer that by following it with these questions. Does the great musician really need an instrument to become one? Or, to phrase it another way, does the instrument have anything to do in creating a great musician? The answer is, as you might have guessed, not really. The instrument is purely incidental, in fact, a great musician can merely whistle and get a favorable audience reaction. Why? because they are born with the internal knowledge of the universal language of music, also know as, the gift of music. The possession of that knowledge or talent is the critical difference between the great musician versus the instrumental player. The great musician usually has a clear connection with the musical language within themselves, making it easy for them to express it. To the extent they can tap into that energy the greater they can reach the audience. The not so great musician, on the other hand, has a blurred connection, if at all. You can play your instrument till you drop dead, if the notes are not connected to your internal language of music you are merely playing notes, not music.
The unfortunate difference between the language of music and any other language is that, you cannot learn it. If you are born with it, you can learn how to better tap into it, if you are not born with it however, you might as well take up Spanish. For those born with it, practicing your music should involve great attention to the connection of yourself to the language of music as much as the time spent with your instrument developing your technique. By that I mean, in order to tap into the energy of music easily, you will have to spend a great deal of time taking care of your physical, mental, emotional and spiritual health as opposed to just concentrating on your instrument. Ultimately, it is your usefulness, in terms of inspiring and touching your audience that makes you a great musician.