What is the point of the pics on the cover of the books?

I saw this on Yahoo Answers, and I think it's the best explanation.

"Twilight: the apple represents the forbidden fruit. it represents the forbidden love between Bella and Edward

New Moon: there isnt a true meaning for the bloody tulip. Stephenie had no say in the cover. but the title itself has a meaning. the new moon is the darkest time in the lunar cycle. so it represents the darkest time in Bella's life since Edward left. but if you want my opinion about the tulip i would say it represents how bella was left "bleeding" when Edward left.

Eclipse: the tearing ribbon represents choice. Bella has to choose between her love for Edward and her friendship with Jacob. she can't decide therefore the ribbon is tearing.

Breaking Dawn: here's my theory. the red pawn in the background represents Bella as a human. she's weak, warm, and she blushes a lot. The white queen in the front represents Bella as a vampire. she's strong, cold, hard, and pale. it represents her transition into a new life as a vampire with Edward forever!"

Hope that helps. :)

Twilight- the apple (forbidden fruit) represents Edward & Bella's forbidden love.

New Moon- The red is Edward and the white is Bella. The little petal floating off to the side represents Edward leaving. The flower (Bella) shows that even though Edward is gone, she still loves him and can't get over him.

Eclipse- Bella's the ribbon. She has to choose a life. Spend eternity with the Cullens or grow old and keep all her family and friends. She's torn between the choices.

Breaking Dawn- The red piece represents Bella at the beginning of the series. If you look, it is three spaces behind (three books behind). The white piece represents her as a vampire. She's stronger after everything she's experienced and she brings about the win for the Cullens from the Volturi.