What the meaning of the blind man will not thank you for a looking glass?

Answer 1

It means giving someone something of no use to them will earn you no gratitude. For example give a man with no feet shoes and he wont thank you because he obviously doesn't need shoes and can't wear them he may even find it insulting.

Answer 2

This phrase means that certain people may not appreciate something if they are unable to perceive its value or significance. In this case, the blind man cannot see his reflection in the looking glass, so he cannot understand or be grateful for it.