Who is "He"? …..He divined with three tortoises, and they all indicated good fortune. He then open the lock and looked at the writing: it too indicated good fortune. He said, “The configuration shows that the king will not suffer harm, and that I, the small child, have obtained a renewed mandate from the three kings. It is the long range that must be considered, and so I await my fate. They will take care of our king.” He returned and put the scribe’s record in a mental bound box. By the next day the king had improved.

He is the "small child"

Explanation:

As the text states, the person in question starts talking after the divinations. He starts by acknowledging the existence of a king that seems to be sick (the king will not suffer harm + the king had improved). So the person is not the king.

Then he states "I, the small child, have obtained a renewed mandate from the three kings. It is the long range that must be considered, and so I await my fate". Therefore, it is possible to inferr that the person talking is the small child.

the name of the theory is landmass theory.