Why?

Yu Zheng Xi looked at his master and sighed, but he didn't say anything more. 

He knew more than anyone aside from his third senior brother how heartbroken Traveling Doctor Liu was when he lost his seventh disciple many years ago. 

There were many disciples whom Traveling Doctor Liu had taken. 

And this old man loves and care for each and every single one of them. 

But fate was not kind enough.

Because of the position and situation involving these disciples, they were bound by constraints of the world and also various other matters. They couldn't escape and had to face their own demise that was brought to their door. 

It was Traveling Doctor Liu's dream to spread his medical capabilities to the entire world.

But it was only after facing the death of his seventh disciple did he realize how naive he was and that there were many constraints that they all faced. They couldn't escape even if they wanted to.