Glass is also a solid object, yet how are we able to see through it?

The molecules of solid matter are usually
packed tightly together, and therefore do not
allow light to pass through them. In liquids
and gases, the molecules move about freely
and there is a lot of space between them.
That is why light is able to pass through these
materials easily. Glass is made by first melting
sand, and then cooling it. The substance made
has the rigidity of a solid, but still has the free
moving molecules of a liquid. So the space
between the molecules of glass allows light to
pass through, although glass itself is a solid.