Everything is a mirror along some frequency. Everything has a transmission, absorption and a reflection spectrum with regards to how it treats light (and sound also).

A silvered mirror makes this all the more obvious but in all due honesty even when you're staring at a brick wall, your reflection is right there in that brick wall though you cannot really see it except its Other as your shadow. In other wavelengths such as IR, or radar, your reflection is there clear as daylight, if only we could see.

This also means that when you read a book or use a computer, you're being reflected into the book and back to yourself, and back again and again; the same is true for walls, the sky, whatever. The words you write here are like your face in the sense that everything in front of your face reflects light off it (and all the crazy wavelengths that reach through the skull).

This is lightning as viewed through an X-Ray imager in combination with the visual spectrum: