Imagine there is a huge warehouse, which is dark, and you live in this warehouse with one flashlight.
Everything you know about this warehouse is seen through the light of this one small flashlight.
Whenever you want to look for something, you may or may not find it, but it does not mean the thing does not exist.
It is there, but you just haven't flashed your light on it. You can only see what your light is focused on.
Then one day, someone flicks on a lightswitch, and for the first time, you can see the whole warehouse.