What is the meaning of the sentence " Man's grasp exceeds his nerve "?

It means that people's capabilities or what they could achieve exceed what they have the nerve to do. Like if someone had the smarts and talent and potential and whatever to make a great scientific discovery, but they don't do it because they're scared of the results or of what people might think. They don't have the guts.

He has alot of motivation and can grasp knowledge fast before his body can process it.