Don't judge a book by its cover

Don't judge a book by its cover.What do I actually mean?It's something got to do with me again.

My class had a new student this year.So I knew he was from a very bad school.So I plan not to mix with him at first.Later ,I was sitting next to him.So when I knew he got top in some of the subject,I realise it's very bad to look down on people.

so remember don't judge a book by its cover this word helps me.