fredthebear: Black comes out aggressively! White must play carefully. Then White makes use of the open e-file under his control. White is able to trade his knight for Black's centralized bishop, which is a positional factor later in the game.
This becomes a battle over isolated pawns. Black cannot hang onto his d-pawn passer, while White does retain his b-pawn passer. White has a big mobility advantage in the endgame when his long range bishop can protect either pawn on each side of the board from a distance, allowing the White king to go freely on the attack.
In the final position, White's bishop has the Black knight corralled on the back rank. If the knight tries to leave, it will be captured and the b-pawn promotes. With the queenside neutralized in White's favor, the game is reduced to a simple K&P vs. K on the kingside. White has the advantage here too, as the White king is way out in front of the passed g-pawn, so it will promote. Remember the rule: A king on the 6th ahead of it's passed pawn will be able to get control of the promotion square no matter who's turn it is to move. Or, the White king could march over on the dark squares and take the Black knight while the Black king must eye the g-pawn. Thus, Black resigned.
Looking back, I suppose Black could have sacrificed the exchange, rook for bishop and pawn (or pawn and bishop) on the 31st move. This would have kept play on one side of the board (albeit down the exchange) with White now having to deal with Black's protected d-pawn passer. This appears to slightly improve Black's drawing chances. However, David Janowski was not one to play for a mere draw at best!
Janowski detested endgames and was known for attacking with the bishop pair. He and Siegbert Tarrasch are the only two players to have defeated the first four world champions.