What do flies think about when they’re walking on a clear glass window?

Just moments ago a fly was enjoying the open outdoors when a door opened and the fly flew inside.

Now it’s flying around trying to figure out where, in all this air it’s flying around in, is there a place getting around the solid clear wall it had never encountered before.

Flies don’t know walls or doors.

How short is a fly’s life?

If we double, tripled or increased its life ten times, would a fly ever know what a house is?

Then why do we call them house flies?

Do they call themselves anything?