Outdoors: Monocular vision
In the European sculpture wing of most art museums, one is confronted with a bewildering assortment of mythological gods and goddesses.
I can usually recognize the Roman god of doors and transitions, Janus, because he has two heads, one looking forward and one looking back.
To see both forward and backward, a double face would be necessary.
Human eyes, located on the very front of face, produce what is known as binocular vision.
The two eyes work together to provide an image, complete with depth perception. Binocular vision is so much a part of us, we find it difficult to imagine seeing any other way.
But many birds, fish and insects rely on monocular vision.
They also have two eyes, but their eyes are located on the sides of their heads.
Each eye works independently.
How their brains actually process the double images, I'm not sure.
But I do know that these animals can see to both sides simultaneously.
This has immense survival value, for the animals can detect predators coming from either direction.
Of course, monocular vision has its problems.
The creatures cannot judge distance, and they have to cock their heads if they want to pick something up. But it works for them.
January was named for Janus, so as we start our new year looking into the future, perhaps we should also look back to remember the lessons we learned in the dreadful year we just survived.