Why we need light but also the darkness…?

Without light, there’s nothing. So dramatic, is it…?
Without light, there are no plants and therefore animals…
Without light, our world lacks shape and form and colour…
Through the vision and technical skills of modern architects our homes have been opened up to the pleasures of natural light, and for the first time in history we’ve had on-tap, artificial electric light which has extended our days and irrevocably changed the way in which we live.

While it is an absolute fact, that why we need light, I also suggest that we need darkness. If we combine between light and darkness, it will be creating the dramatically effect trough the shadow when light hit an object. Darkness adds modulation, contrast, subtlety, excitement, restfulness, and mystery.

Light and dark are not only physical entities, they also have powerful cultural associations, but both throughout the world in the past and present.
Heres, I try to explain the benefit of lighting for architectural product.