That’s pupil in relation to the eye, not the pupil that constitutes a student. Before we get into the specifics of the word, I want to help you envision what the pupil of an eye is synonymous to. A pupil by definition is “the dark circular opening in the center of the iris of the eye, varying in size to regulate the amount of light reaching the retina.” It is a deep black, like a void right in the middle of the eyeball.
When I try to imagine what other objects are synonymous to this, I picture dome cathedrals built during the Renaissance period, namely the Pantheon in Rome. In the pantheon, a giant dome towers into the sky, and if you look up into it, you’ll notice a giant hole right in the middle where all sides of the dome come to meet in one place. Its made of a giant circular stone called the oculus. It’s been assumed that this was used to let light in, or the heavens. But it also acts as a sort of keystone to keep all the sides in place. It is the center stone that helps the dome from collapsing. Well, think of a pupil in the same way. If you use a little creativity, you can imagine that the pupil is what holds the rest of the eye together, it is a keystone in itself and the eye wouldn’t be able to stand on its own without it. That being said, the word “augasteinn” is a combination of “auga” meaning eye, and “steinn” meaning stone. Eye stone. The keystone of the eye.