In 1988, I created the following unfinished sentence and received these responses:
The hallmark of a true musician is...
...playing or attempting more than one instrument, playing with taste, and not being an egomaniac. (Jon B.)
...love of all music. Dedication toward one field--Classical, jazz, or modern--will lessen the total musician. The true musician can appreciate something that is well-written. (Elizabeth F.)
...a feeling for the music...being able to become one with your instrument...or someone with an idol who follows him/her like (s)he's a god and uses every technique (s)he uses. This person would also have pictures and such and know where (their idol) is performing at all times. (Gina L.)
...mind over fingers. (Scott S.)
...waking before 9 a.m. (Mark W.)
...waking after 11 a.m. (Mark M.)