William Blake: fine artist or illustrator?

To me, an illustration is used to get across a certain point, or to persuade the viewer to believe a certain way. On the other hand, a piece of fine art is accomplished for the sake of art or personal enjoyment; it can be interpreted in many ways.
William Blake was both of these, I believe. He was born and raised to be a print maker. Almost any print maker would be drawn to illustration more than fine art, because words are used in print all the time, and words are very persuasive. He painted many illustrations for books and title covers.

This one is definitely an illustration, as you can see the way the type is mixed into the scene itself (title for Songs of Innocence).

Blake also painted for the sake of art, however. In this example, we see how he sometimes painted his visions (Ghost of a Flea, 1819 - 1820).
Many people claimed that William Blake was not completely there mentally. After reading some excerpts of his writings, I think I agree. In my mind, mentally unstable people don’t always think about what they are doing, and sometimes, just do it. For no rhyme or reason. That would be fine art. Also, in some of his works, it is hard to say whether it is fine art or an illustration, because most of his work is just pleasing to the eye, even if there is a point he is trying to get across.