We can draw similar circles for just about any domain: how about a circle representing all the computer science fundamentals (and the incremental innovations built on top of them) or a circle for psychology?
When the world is about to face an apocalypse and there is only a limited amount of information you can pass on to the survivors, we should be giving them the points on the circle. Rest of the knowledge can be incrementally (and mostly relatively quickly) derived from them.
There are several gaps in our circle of knowledge. These are the fundamental principles waiting to be discovered. What is the concept of spirit? The reason behind Cancer? What other gaps do you think exist in the circle of knowledge?