An echo is a good way to describe the photogram, which is a visual echo of the real object. That's why I like to work with the photogram, because the contact with what is represented is actual. It's as if the border between the world and the print is osmotic.
It seems to be the special peculiarity of human beings that they reflect: they think about thinking and know that they know. This, like other feedback systems, may lead to vicious circles and confusions if improperly managed, but self-awareness makes human experience resonant. It imparts that simultaneous "echo" to all that we think and feel as the box of a violin reverberates with the sound of the strings. It gives depth and volume to what would otherwise be shallow and flat.
Seated one day at the organ, I was weary and ill at ease, and my fingers wandered idly over the noisy keys. It seemed the harmonious echo from our discordant life.