From a thermodynamic point of view, Professor Mauro explained, glass has a tendency to become solid. At the molecular level, glass behaves more like a viscous fluid than a solid, but we think of it as a solid because glass molecules move so slowly. Philosophically, the glass we're looking at is interesting, Mauro said. When we look at other substances, we learn about glass. Yet, right under our noses, there is a scientific marvel - a substance that behaves in a fascinating and unique way, one that defies easy classification. It makes up our lenses, microscopes, telescopes, screens and eyeglasses. Glass allows us to see the world more clearly, yet we rarely really pay attention to it.