When you say you like a portrait of a girl, are you saying you like the painting or are you saying you like the girl?
How much does the attractiveness of a painting depend on the attractiveness of the things that are painted in it?
A tourist with a camera is provided with various things he or she wants to take pictures of.
And one of the photos he or she took may strike you as quite good, -- so good that you may want to call it a work of art.
Now, what makes it so good?
Is it the way it is composed, or the attractiveness of the things or the people photographed in it?
When you take a picture of a girl, you cannot change her face or figure.
But when you paint her, she is an inspiration, not just a subject.
You are looking at her, but you are also singing.
Then what are you doing when copying somebody else's painting?
Are you singing that person's songs, or are you singing your own?