What killed Philosopher Tasyo in Chapter 57-59?

Tasio, an elderly man, was already ill, though we are not apprised that he was sick due to anything other than old age.

He was an old man, pale and emaciated, wrapped in a woolen blanket, supporting himself with difficulty on a staff. It was the old Sage, Tasio, who, on hearing of the event, had left his bed to be present, but his strength had not been sufficient to carry him to the town hall. The old man followed the cart with his gaze until it disappeared in the distance and then remained for some time afterward with his head bowed, deep in thought. Then he stood up and laboriously made his way toward his house, pausing to rest at every step. On the following day some herdsmen found him dead on the very threshold of his solitary home.