The doctor has just left me. At last I have got at something definite! For all his cunning, he had to speak out at last. Yes, I am soon, very soon, to die. The frozen rivers will break up, and with the last snow I shall, most likely, swim away ... whither? God knows! To the ocean too.
These are first few lines from Ivan Turgenev's story, "The Diary of a Superfluous Man". What does "For all his cunning" mean here?