Then it was that Doctor Joe announced one day before the return of David and Andy from the trails, that the operation could be no longer delayed if Jamie's eyesight was to be saved, and that to attempt to delay it until the ice cleared from the coast and the mail boat came to bear him away to New York would be fatal.
After making this announcement, Doctor Joe revealed the fact that he had once been a great eye surgeon.

With Thomas's consent he offered to perform the operation on Jamie's eyes.

Thomas had unbounded faith in his friend.

Doctor Joe operated and Jamie's sight was saved.
In curing Jamie, Doctor Joe discovered that he himself was cured, and that he was again in possession of all his former skill.

It was quite natural, therefore, that he should wish to resume the practice of surgery.