It is how our brain assembles the two different images from our
eyes that allows us to see three dimensions. To see how each of our
eyes view objects in a slightly different angle. Try this
test.
Close your right eye.
Looking through your left eye, line up your finger
so that it covers the line.
Keep you finger in the same position and close your left eye and
open your right eye.
Notice the line looks like it moved and is now visible. Reverse
this test and notice the line moves in the other direction.
You have now observed how how each eye sends a slightly
different view of the same object to the brain.
