I think that the author is giving a commentary more on the nature of art than of literature when Ellen talks about creating a picture of kittens for Dora and Nadine. Ellen does say, though, that she learned how to draw cats, as well as covered bridges, out of a library book. Ellen would prefer to draw "one of (her) brooding oceans...(that look) strong and beautiful and sad at the same time and that is really something if you think about it." Ellen decides that Dora and Nadine will not be able to understand her own creative work, however, and so she chooses to do a picture of cats, even though "once you look at it one time you have seen and felt everything you will ever see and feel about those cats."
The author seems to be pointing out the limitations of information gained from books as opposed to that which springs from the imagination. Ellen recognizes that, although she can derive the ability to draw from a library book, she cannot get the same substance in her work that she would if she had used her creative powers. Knowledge gained secondhand from literature is no match for originality and experience, although it does provide an avenue in which one can relate to others. When all is said and done, however, a picture copied from a book lacks the depth and feeling of one created from imagination (Chapter 14).
A few pages earlier, the author does point out a true value of literature, and in particular, storytelling. Ellen is annoyed when Nadine and Dora say that Ellen's Dad is "up in heaven strumming on a harp with the angels," comparing their account of her father's whereabouts with the fanciful tale of them saying that her daddy isn't dead, but is instead "just up at the North Pole working away on scooters and train sets like a good elf should." Although Ellen does not buy into these fictional accounts created to make her feel better, she does concede,
"...they get some comfort out of the made up stories. And if that helps them get along maybe I should not poke fun."
Here, the author addresses the essence of literature and storytelling throughout history. People make up stories to explain things, and to make them feel as if they have some understanding of and control over the events going on around them. Literature is valuable for this purpose (Chapter 13).