In chapters 1-5, how was the stranger's mental and physical condition reflected in his appearance?

He looked like an eccentric bush doctor,

"He was small in stature, with a furrowed visage, which, as yet, could hardly be termed aged. There was a remarkable intelligence in his features, as of a person who had so cultivated his mental part that it could not fail to mould the physical to itself, and become manifest by unmistakable tokens."