Part 176: System of MagicA foundation upon which to create magic. In particular, it refers to a system by whose shared usage magic power can be gained without conscious effort. You could say that writing down their own system of magic and leaving it to future generations is one of a witch's life works.
However, systems of terrific magical power are correspondingly difficult to comprehened, and shared usage of them is troublesome. As a result, none will appear to bear the burden.
If a system's magical power is simple, there will likely be no difficulties sharing it, but as a result, the system will be reduced to having no greater effect than a simple good luck charm, and will ultimately be forgotten.
Leaving a system of magic for later generations while simultaneously maintaining that balance is the true joy of witchcraft.