Here's why:
* Needle: A compass needle is a crucial tool for navigation.
* Pole: The North Pole is a fixed point, representing the ultimate destination for a compass needle.
* True: This word emphasizes the absolute correctness and reliability of the direction the needle points.
Therefore, the phrase implies that something is as certain and unerring as a compass needle pointing north. It signifies a strong conviction or a clear and unwavering path.