The beautiful human eye:

This eye is designed to bond with other human eyes. The bonding results from the striking contrast between the iris and the sclera, the white part of the eye. A human can communicate with just the eyes. No words are need, nor the movement of the head. Just move the eyes and a message is sent, a bond is made. It is here we find the reason for the popularity of sunglasses in the realm of professional poker. Those socialist eyes betray the player:

Like a poker player sporting aviator sunglasses, a species of squid has developed a clever way to camouflage its eyes from potential predators. In the deep ocean, the light coming from behind an approaching predator is identical to that coming from behind its prey — so an animal that can reflect this light will appear invisible.

These squids are really something else. But what their eyes do in nature is what sunglasses do in the circle of human sociality. When we can't see the eyes, the soul of the other becomes invisible.