Why first "A" is used in sentence "A little knowledge is a dangerous thing."isn't a superfluous ?forgive me.I am a novice.
Confusingly, other similar-looking maxims have a different thrust, saying that even a small amount of something (and 'a little X' means 'a small amount of X' not 'a small X' where X is non-count) can be beneficial:
- A little [bit of] love goes a long way.
- A little effort goes a long way.
- A little kindness goes a long way.
This is different again from the claim that one can eke out certain commodities:
- Saffron is very expensive, but a little goes a long way.
- A little knowledge is a dangerous thing.
contrasts markedly; it means that people who don't have the whole picture but think they know the best solution to a problem can actually make the problem worse, by confidently offering the wrong advice (whereas people with no knowledge at all would keep silent).
The difference between 'He showed little love' and 'He showed a little love' say has been covered before on ELU.
The standard "saying" does include the article, and the standard meaning is...
a small amount of knowledge can mislead people into thinking that they are more expert than they really are, which can lead to mistakes being made.
It's not particularly idiomatic to discard that leading article in OP's exact case, but consider...
1: Little of my money is easily accessible
2: A little of my money is easily accessible
...where #1 means I can't easily access most of my money - only a small amount is easily accessible, and #2 means I can access some of my money, but not much.
It is worth nothing that
A little knowledge is a dangerous thing.
is an altered quotation. the original was
A little learning is a dangerous thing.
From a poem by Alexander Pope. The opening quatrain reads:
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There shallow draughts intoxicate the brain,
And drinking largely sobers us again
meaning that slight, superficial study leads to misunderstanding and even fanaticism, and extended study leads to a reasoned, moderate course. This verse is an except from Pope's An Essay on Criticism (1709).
If the article were omitted, giving
Little knowledge is a dangerous thing.
that would drastically change the meaning, meaning that most knowledge is not dangerous, only a few bits of knowledge are dangerous. That is not at all what the usual phrase is intended to mean.
In general "A little X" means a small amount of X, particularly when X is non-countable. "Little X" generally means the same as "Few X", "Not many X", or "Not much X". Sometimes the meaning is similar, sometimes it is very different.
- A little sand is used in making this type of glass (A small amount of sand is used.)
- Little sand is used in making this type of glass (Not much sand is used.)
In the above case the two meanings are similar, but there is a different emphasis.
- A little taste is needed to appreciate the beauty of Monet's work. (Some taste is needed, and this is probably an ironic understatement, meaning "a lot of taste".)
- Little taste is needed to appreciate the beauty of Monet's work. (Not much taste is needed, that is, almost anyone will perceive this beauty.)
The two meanings are here pretty much opposites.
Whether or not the 'A' is there actually reverses the meaning of the sentence.
A little knowledge is a dangerous thing
Means that when you have even a tiny bit of knowledge, that can be used for bad purposes ('a dangerous thing'). This is an exaggeration of course, but it's a proverb that implies that knowledge bears power.
Little knowledge is a dangerous thing
This means that having little (not much) knowledge is a dangerous thing, it implies that it is disadvantageous when you are not very knowledgeable.