Books about artwork, unless they are intended for a general audience, ought to include discussions of both the meaning behind the piece of art and the background of the artist who created that piece  If they do not, they are flawed
Gardener' s book on paintings of the Renaissance era describes the significance of the paintings, but fails to mention that the artist of several paintings discussed at length in the book is considered to be one of the greatest artists of all time
Gardener's book is intended for a general audience.