In class we talked about the fact that written language is constructed from symbols (letters) that were developed from images. These symbols have a long history of development that is well described in this article:

http://ilovetypography.com/2010/08/07/where-does-the-alphabet-come-from/

Let's remember that written language is a product of our need to describe a picture or thing that we already know. It only makes sense then that in learning kids need the picture before the words (comprehension before decoding). This makes the primary task of teaching more about building the pictures, images and concepts first - then teaching the letters (symbols) that describe them. Thus, we use symbols, pictures, stories, and experiences to shape language skills, not the other way around.