The Hundred Refining Threads Soul technique transformed the soul into a hundred fine, thin threads. A thread, however basic it could be, was a solid form, and to perfectly master this technique, one would need to refine their soul into a hundred such threads.
The technique also explained why the shape of a thread, rather than anything else, was chosen. Since it was already difficult for humans to control their souls, attempting to refine their soul into any complex solid forms like swords would make the process nearly impossible for humans to accomplish.
Thus, the method of first refining the soul into small and simple shapes came into existence.
'Moreover, in Apprentice Rank, one could only have limited control over the soul,' Max thought. The higher a person's rank, the more control they would have over their soul, but that didn't mean someone in Seeker Rank would be able to refine their soul into a sword shape on their first try.
