“Art is the most effective mode of communication that exists.” – John Dewey
I might argue that art, or more exactly, the arts, are the only forms of communication that exist. There are only so many ways for humans to communicate, and each one can easily fall into one of the arts. The arts are about communication (and therefore comprehension, too). We tend to think of communication and comprehension as being owned by literacy education but literacy education or what many call, language arts, actually falls under the arts umbrella.
Painting, sculpting, writing, photography, design, film, dance, music, singing, acting etc. are all ways that humans communicate. They all require comprehension skills to be understood.
When students study the arts, they are really exploring all the ways that humans have developed to communicate. This is one reason why quality arts education matters so much.