This sentence means that when you encounter difficulties and setbacks, you feel confused and helpless. You can look at the problem from different angles, seek help and guidance from different people or things, and finally find a bright direction and get out of the predicament. Crow, as a black bird, can fly freely in the dark, while eagle, because of its light body color, is difficult to tell its direction in the dark and easily gets lost. Crows, on the other hand, can guide the eagle to fly in the light, that is, guide the eagle in the dark and help the eagle find the bright direction.