Today, when I read a article, I found that it's very good, therefore copy to here.
Down to earth means being open and honest. It's easy to deal with someone who is down to earth.
A person who is down to earth is pleasure to find. He or she accepts other people as equals.
A down to earth person is the oppsite of someone who acts important or pround. Down to earth people could be important members of society. But they do not consider themselves to be better than others who are less important. They do not let their importance " go to their heads." some one who lets something go to his head feels he is better that others. He has a "big head".
A person who is filled with his own importance and pride is said to have " his nose in the air". often the person who has a big head and his nose in the air has no reason to feel better than others. He surely is the oppsite of someon who is down to earth.
American use other expression that is similar in some ways to down to earth. The expression is " both feet on the ground." Someone with both feet on the ground is a person with a good understanding of reality. she has what is called" common sense". she may have dreams. But she does not allow them to block her understanding of what is real. the oppsite kind of person is one who has his "head in the clouds". Someone with his head in the clouds is person whose mind is not on what is happening in real life.