Mapping is the spatial representations of complex concepts, starting with concepts that with well understood basic principles, and then branching out in in progressive small steps. The Common Vein uses the imagery of a tree for spatial representation as in a tree of knowledge and also as a tree of understanding and enlightenment. Implied are key elements of roots, trunk, and branches.
The trunk as a single element reflects the central core concept one is trying to understand.
In this case the central trunk is the kidney,
The roots represent elemental principles which reflect the foundation of the concept. They are inarguable black and white principles.
The branches are the different states that may occur within a given environment and with time. Both have have infinite divisions with progressive complexity.
The first step therefore using tree mapping is to identify the single core element that you need to understand. The second step is to identify the first level of the root elements, and thirdly to identify the first level of branches.