What the eye may not see . . .
We are always busy with denying what we can not see.
But see . . . It's a lot of things which are present although we normaly cannot see or hear it.
Like the sound barrier . . . We cannot see that it actually is a kind of wall controlling the sounds around. To human that means, it is a lot of sounds the human ear cannot hear.
But when an airoplane passes the sound barrier, a camera actually can capture "the wall".
As you SEE . . . The plane is actually passing through an "invisible" wall.