What does "nothing need prevent him from doing it" mean

[Steven Mai]

Hi all,

Can you tell me what this sentence means? It's from a book called "The Story of Abraham Lincoln".

"If a man really wants to serve his country, nothing need prevent him from doing it."

What does "nothing need prevent him from doing it" mean?
When I first heard this word, I thought oh maybe the "need" here is an adjective, or it might well be a homonym, but then I looked at the text, and looked it up in a dictionary, Googled it, I still don't understand what it means.

It seems a verb to me, so I thought is it one of those verbs that are not necessarily followed by "to", but even if that's the case, "nothing need to prevent him..."still seems a bit odd to me, also, it should have been "needs" if it's a verb, right?

Can you please tell me what it means and what part of speech it is?

Thank you very much : )

 

[GoesStation]

"If a man really wants to serve his country, nothing need prevent him from doing it."

[STRIKE]This is an example of an obsolete use of the subjunctive after if.[/STRIKE] It means there's no need for anything to prevent a person who really wants to from serving their country.

[Edited to strike out misinformation. See post #3.]