During the Renaissance, the five senses were understood to form a hierarchical system from the highest sense of vision down to touch. Vision was correlated to fire and light, hearing to air, smell to vapour, taste to water, and touch to earth.
Perhaps the human fascination with fire stems from the totality of its sensory stimulation. The fire gives a flickering and glowing light, ever moving, ever changing. It crackles and hisses and fills the room with the smells of smoke and wood and perhaps even food. It penetrates us with its warmth. Every sense is stimulated and all of their associated modes of perception, such as memory and an awareness of time, are also brought into play, focused on the one experience of the fire. Together they create such an intense feeling of reality, of the "here and nowness" of the moment, that the fire becomes completely captivating.
Generally speaking (and ignoring questions of styling, API availability, etc.), an ideal Web annotation pattern follows these principles:
Annotations appear in close visual proximity to the primary content.
Their design neither distracts from nor hides the primary content.
The preceding principles are followed regardless of screen width.
The only pattern I’ve found that meets these criteria is FiveThirtyEight’s.
...As it turns out, FiveThirtyEight didn't invent this pattern. It likely originated in medieval illuminated manuscripts which contain “interleave notes” — comments written literally between the lines.