What is a great artist?

What is a great artist? Or a great poet, or a great writer?
It is the one who can give reality to his creation, and makes it live forever.
He is the one who is able to create something that when is finished has, as it were, an independent life of its own, and may deliver a message far other than that which was put into its lips to say.
And the critic?
He is by far a more interesting subject, because he can be a creator in his turn, and whisper of a thousand different things which were not present in the mind of him who carved the statue or painted the panel or graved the gem.