Art?

I read a blog by a friend of mine the other day which expounded on the essence of art. His general conclusion went something along the lines of: "No one can give art any inherent worth other than the artist. It is a mode of self expression, and as such, how "good" or "bad" the art is can only be determined by how pleased the artist himself is with his work of art. No one can say what is and is not art, and when one attempts to make art for anyone else other than himself, he fails to do so." (That, more or less, was his conclusion.)

I replied with a comment that read: "i'd just like to say "amen brother!" couldn't agree with you more. art is inherently and inseparably self expressive."

But, in light of this, I may have to completely retract my earlier statement. But that is something to think on: What is art? And what are the boundaries on works of art?