In Book from the Ground by Bing Xu, the author employs indices as the (nearly) sole means of communicating the narrative. The index of the eye shut and subsequently open is an indication of waking up- it is not wholly abstract, neither a direct representation of its meaning. Much like paw prints are an indication of animal mobility, the visual aids (indexes) employed here rely on the implication of action.
This means that the experience of the story is intuited between indices (excepting Xu’s use of ellipses, which are a symbol. They require cultural context to decipher). The author has, to an extent, consciously obscured the narrative. The content offers little more than a nameless character waking up and going about their day- the obfuscation of this process through index is what makes it entertaining and compelling.
I think this reinforces the idea that subject is arbitrary to storytelling- the way you portray your subject, the medium of it, the unfurling of the narrative, is all that really matters as far as emotional response within the viewer. I already use signs in my stories (everybody does), but this experience has made me far more conscious of them than I ever was. I will definitely think more about the way I’m using signs and differentiate their category and uses.