What is the meaning of a strange thing happened in his head something flittered there in front of his mind like a bat's wing obscuring his idea?

The phrase suggests a fleeting, confusing thought that disrupts the clarity of the person's mind, much like a bat's wing can obscure vision. It indicates a moment of mental distraction or uncertainty, where an idea is present but difficult to grasp. This imagery conveys a sense of disorientation, highlighting the struggle to focus or understand one's thoughts clearly.