Question:
Al Horowitz analyzes this in "How To Win in the Chess Endings" and claims the bishop is futile: "As a rule, a Bishop can check two pawns with the assistance of its King. Here the White King is on the borderline, just outside the critical sector. With precision play Black can win."

He gives

1... d4 2. Kd6 a5 3. g4 a4 4. g5 d3 5. Ke7 a3! and one of the Black pawns queens. Yet my analysis shows White can draw after

1... d4 2. Bd2! Kd3 3. Ba5 Ke2 4. Kb7 d3 4... Kf3 5. Kc6 Kxg3 6. Kd5 f5 7. Kxd4 f4 8. Bc7= 5. Kxa7 d2 6. Bxd2 Kxd2 7. Kb6 Ke3 8. Kc5 Kf3 9. Kd5 Kxg3 10. Ke5 and his King is just close enough to capture the last pawn. I've looked at all the other lines I can think of and can't find a way to bust 2. Bd2! Am I right?

Answer:
It's fascinating and you're right that White can draw by the skin of his teeth. Another try is

1... Kc3 2. Kb7! a5 3. Kb6 a4 4. Ka5 d4 5. Kxa4 d3 6. Kb5 d2 7. Bxd2+ Kxd2 8. Kc5=

How to Win at Chess (David Mckay, 1968) combines four books written by Horowitz in the 1950s: How to Win in the Chess Openings, Modern Ideas in the Chess Openings, How to Win in the Middle Game of Chess, and How to Win in the Chess Endings. On page 113 of book four Horowitz says 1...d4! is the star move, noting: "It is curious that the tempting

1... a5 will not do: e.g., 2. Kb6 a4 3. Ka5 Kb3 4. Be3 a3 5. Kb5 Kc3 6. Kc5 Kd3 7. Bd4 Ke4 8. Bf6 a2 9. g4 and White draws"