Mm... something a bit paradoxal about black plague?

[LucaP1000]

I think it's purely metaphorical. After all he's seen, all he now knows and has been through alongside his infection he no longer considers himself the man he used to be. Regardless of the outcome of his 'adventure' he could never go back to the life he once had because he himself has changed.

Agree. Everyone after a similiar experience, would not be the same anymore. Philip did already know this while he was travelling toward Greenland. If you listen at the Overture intro movie, he says he knew he was leaving everyone, and maybe he won't come back anymore. Philip had two chances: stay at home, but with his father's past obscured, or risk his life but at least know what really happened.