From the abiogenesis, light on Earth celebrates creature existence by, presenting its presence. Flowers are blooming and trees are growing because photosynthesis is happening. If it is daytime, you will find the sun. During night sky is clear but you can see a moon with thousands of stars. Imagining an instant without sun and stars, the sky could be clear as dark. Just now "Close your eyes and try to see something"... here we know, you can imagine things while closing your eyes but you can't see actually, you can't touch physically. Before the invention of the bulb, there were also some sources of light to enlighten dark rooms at night-time e.g. candles, Diya and flaming torches, etc. But time has been changing and from growing human civilization to a man, Thomas Edison invented the first bulb, a light source. From this invention to today lots of changes occurring, currently, the bulb is not just a source of light to see things and compelling things. It is also a way to show the human mental state.
Homes and buildings furnish with light show happiness, standing people with light in a candle march shows emotion and to show support for a specific cause. Light can signify various states of mind of human happiness, support, and emotions all instance, assembling of light can show. Creature of the earth has no colors, a green leaf is not green, a flower of red rose is not red and a blue car is not blue, as things have no own colors. It is light, it is creating the green, red, and blue as they look like. A ray of light contains seven colors in it, as a rainbow shows us. Reflecting and absorbing colors among seven sets a glimpse for a body. Your office, home, and school everywhere, assembling of light affect your daily routine. To cheer your guests' lighting can play a supreme role in your home. If you are sitting in front of your laptop and if it has LCD, do you know? LCD is an electronically modulated optical device. It uses a backlight to produce images in color.
If light can glad your brain then, during rain when darkness surrounds us with the presence of pouring clouds. Unexpectedly lighting in the sky can frighten us for an instant. After some time, clouds removal after raining and a meteorological phenomenon caused by reflection, refraction, and dispersion of light in water droplets resulting in a spectrum of light in the sky out-turn to the rainbow. It can delight our brains again. Once a legend said "Maybe you have to know the darkness before you can appreciate the light" - Madeline L'Engle. Quote has meant in our lives and the real-world also. In a dark room, you can't see anything, so switch on the light.