All the masterpieces of art contain both light and shadow. A happy life is not one filled with only sunshine, but one which uses both light and shadow to produce beauty.-Billy Graham
I guess he is saying that to have a beautiful life you must have both light (good) and shadow (bad).
There is the sun, snow, and beauty in Mount Rainer and there is sun, heat, and beauty in Tuscany.
Both beautiful both different. Both wonderful but different.