The use of ‘few’, ‘a few’’ and ‘the few’ should be used with care. They denote ‘number’. ‘Few’ means ‘not many’, ‘almost nothing’. A ‘few’ is positive and means ‘some at least’. ‘The few’ means ‘whatever there is’.

A few men are free from fault. (Incorrect)
Few men are free from fault. (Correct)
(Here the sense is negative and thus ‘a few’ is wrong.)

Few teams will qualify for the world cup. (Incorrect)
A few boys will pass in the examination. (Correct)
Here the sense is positive and thus ‘few’ is incorrect.

I have already read a few books that are in the library. (Incorrect)
I have already read the few books that are in the library. (Correct)
Here the sense is ‘whatever there is’. ’everything that is in the library’