It says in the Ten Commandments "Do not be jealous." Does that mean that if I see my friend wearing a dress that I really like, I can't be jealous and want the same dress, even if I don't say anything to my friend?
We are all jealous. It is impossible not to be. As long as we are human, we see what others have and wish we could have it too. But that isn't always bad. There are three types of jealousy. Wicked jealousy, dangerous jealousy, and good jealousy.
If you want your friend's dress and you don't want her to have it, that is wicked. Why should it bother you that your friend owns something nice? Even if you want the same thing, you should be happy for her that she has it. To want it instead of her is plain mean.
So let's say you don't mind that she has her dress, just you want one too. Is that ok? Well, it's not wicked, but be careful. When you focus too much on what other's have, it leads to being unhappy with what you have. Instead of being satisfied with all the good G-d has given you, you always want more. This has no end. Eventually you'll have bad feelings toward your friends when you can't have it all. So this type of jealousy is not wicked, but dangerous.
But then there is a jealousy that is good. That is being jealous of someone else's good deeds or fine character. When you see a friend who is kind, generous, forgiving, disciplined or trustworthy, and you say "I wish I were like that," this is good jealousy. In fact, this is why we have jealousy in our nature. It can make us want to be a better person.
The Talmud teaches, "The world cannot exist without jealousy." Without it we would have no drive to become anything. It just depends how you use it. Be jealous, but for the right things. Your friend's dress will one day go out of fashion. Goodness never will.
Thanks for a great question. I wish I asked such good questions when I was eight years old. I am glad you are my daughter. Otherwise, I'd be jealous.