You can’t have a left without a right, an up without a down, success without failure, a good experience without a bad one and so on; it is a world of duality.
There are two poles or opposites; the difference between the two extremes is called polarity. Within every failure there is potential for success. Within every problem there is a potential for opportunities. Everything in life has an equal opposite. It is up to us as to what side we choose to focus on and experience.