The world is not beautiful therefore it is, so look around with new eyes. You'll be amazed by how the simplest thing has inner beauty. Basically it means that you have to reevaluate what you classify what you define as beautiful in order to open your eyes and see real beauty.
If you want the rainbow, you must put up with the rain
If you want the best, you have to put up with the worst. Or even, in order to experience something as beautiful and wonderful as a rainbow(good things), first you have to put up with the rain.(bad things).