Grammar parsing for "if need be"?

Question

I have the following question. There is an idiom 'if need be'. The meaning is clear, but I can't comprehend it from a grammatical point of view. How should I parse it? 'if [smth] needs to be'? Why not 'needs' then? The question probably is silly...

Answer 1

"If need be", like "thus far" are both older forms of English that are still used in English writing and occasional conversations today. As an author, I use both phrases off-and-on in my writing. "If need be" is another way of saying "if necessary".