Without light, there would be no trees, no grass, no plants at all. We humans would cease to exist. Only recently has the phenomenon of light deprivation in Northern climes been recognized as a valid reason for a discomfiting psychological disorder that makes people feel depressed and edgy. Light is dependent on the weather, the season, the time of day and geography. Light is also affected by, and affects, the materials it encounters.
Some materials absorb light, some refract it, some reflect it.
In addition, when partnered with paint, light and color react in myriad ways to alter our perception of space. Light, in fact, is a prism of colours. When the sun slants through a misty curtain of rain, we can see that prism. It's called a rainbow. Fashion designer Alexander Julian employed the rainbow when he painted every surface in the striking stairwell of his country house a different color.