the significance of the title

Source for the following excerpt can be found below;

This title works on a few levels. First of all, it is quite simply a portrait of an artist. Second, it is a not-so-subtly-hidden of the artist, James Joyce himself. Third, the title places the book in a certain tradition of self-portraits. Many famous painters and sculptors created "Portrait(s) of the Artist(s);" in calling his book by this title, Joyce compares writing to the fine arts – after all, there’s a reason it’s not called something like Biography of the Writer as a Young Man, which really isn’t so catchy.