It can be further simplified by taking it down to 2 dimentions.

Imagine an endless sheet of paper.

Then put that dot on that sheet anywhere. Ask the dot, as you in the third dimention (up) look down on it) where it is, and the answer can only be "I am here". You ask "Where is here?" And the answer comes back "I am here. Where are you? I can hear you but I cant see you."

The dot has no concept of "up", so you cannot explain to him that you are in his presence. So to prove it, you move down through that sheet of paper. Dot senses your presence, and can still hear you, but you are only a veil of your whole as you pass through his 2 dimentional plane.

You disappear as you pass under the infinite sheet of paper, and Dot goes to work trying to explain this notion.

Dot is alone on this infinite sheet of paper and starts to ask where he is to himself. So he wanders around the sheet of paper and asks again, "Where am I but here?"

Then you put another dot on the paper. Now Dot and Dot 2 can see each other. Now you have time. Dot has distance & Time! He knows that it will take x amount of time to get to Dot 2. Now his question of "Where am I?" has meaning. "I am over here!" he can say to Dot 2. And Dot 2 has some location.

And Dot can ask Dot 2 meaningful questions now.

Now imagine that this infinite sheet of paper is one in an infinite stack of sheets with other "dots". They can never see each other, but they are all there amongst each other. (Multiple universes all occupying the same space in another dimention - the third in this case)

This isn't my idea... it's just a really simple way to explain how easy it is to see how hard it can be to contemplate something you can't see, but obviously exists.