Information displays should be annotated, combining words, images, graphics, whatever it takes to describe and explain something. Annotation calls out and explains information and, at the same time, explains to viewers how to read data displays. Good annotation is like a knowledgeable expert/teacher at the viewer's side pointing and saying, "Now see how this works with that, how this might explain that..."
Yehudi Menuhin, a great violinist, marked up a score for Bach's Sonata No. 2 for Solo Violin. Penciled annotations show real-time performance strategies. To outsiders, insider markups appear chaotic and cryptic, but these personal annotations are for Menuhin's eyes, the only eyes that matter. All can learn from this useful workaday grid strategy: a relevant and intense data layer can become a coherent substrate scaffold upon which to overlay additional information. Maps do this all day long.
We can easily imagine from our own experience why fire might be used as a symbol of the life of a house and the family that lives there. The fire was certainly the most lifelike element of the house: it consumed food and left behind waste; it could grow and move seemingly by its own will; and it could exhaust itself and die. And most important it was warm, one of the most fundamental qualities that we associate with our own lives. When the fire dies, its remains become cold, just as the body becomes cold when a person dies. Drawing a parallel to the concept of the soul that animates the physical body of the person, the fire, then, is the animating spirit for the body of the house.