What is formal resonance in photography?

I believe it refers to that which causes you to make a connection between images that you would not make if seen quite separately. Shadow, shape, texture and intangible things such as emotion are things that could induce the connection. The images therefore have a relationship or "resonance" with each other. This may not be a great example, but if you saw a picture of a Bowling ball, you probably would not think of a grape. But if I showed you a photo of a purple bowling ball and a close up of a grape, the color, shape or other attributes may cause you to make the connection. That which creates that connection becomes the formal resonance.