I have a question:
If an artist chooses a medium to communicate his or her messages, and through years of persistence and practice succeeds (via recognition?), then one might confidently say the artist is a master of that medium. Tomorrow, if the artist has a new message, he or she can use that mastery+medium to communicate it to us.
If this is the case, how can anyone accept a literary definition of art from the artist, or even a commentary of it for that matter, simply because language isn't the medium the artist chose? E.g., Picasso could communicate with paintings, but why should we assume Picasso could communicate the meaning of art with words? If he could do it just as effectively, he would have become a writer or poet. After all, artists are not writers or poets or linguists or epistemologists or historians, etc.
Similarly, how can a dictionary definition of art or style have any practical value to an artist, just as the dictionary meaning of the word 'love' can have any practical significance to lovers?