Imagine that you're going to a movie. You walk into the theater and suddenly notice that you can not find your keys. You stop and wonder if you left the keys in you car's ignition. Imagine you walk back to your car, look inside its window, and see the keys hanging from the ignition. Not all factual issues are this easy to resolve, however.
Many factual issues depend upon a tool or instrument that enhances one of our senses .
For example, in order to see objects that are far away we often rely upon telescopes. To see things that are small we often rely upon microscopes. To hear things that are faint we often rely upon a stethoscope. It's important to remember that these instruments all have something in common. They all help enhance one of our senses.