Many of you have never seen one of these:

A WW-II tank periscope prism; unfortunately, there's a bit of deterioration evident on the one. There's about a 5/8" recess between the top of the
frame and the prism face, just enough to fill with water and float a dry fly. Here's a dry fly, floating in a "classic" way that seldom is the real
world condition, supported on hackle points and tail, with the hook above the water surface.

Here's a picture of the fly, taken through the prism with the combination of a light shining through the prism plus the ambient light in my kitchen.
(I can sit the assembly on top of my fridge and shoot away.) This is the way most of you like to think is the way a trout sees it. In this case,
a nice pale yellow body. The preponderance of light, coming from below, shows the color of the fly's body.

And here's a picture taken through the prism with the light bouncing off the ceiling plus the ambient light passing through the prism plus the light reflecting off the waters surface.

"You'll wonder where the yellow went ...." but, like the tank prism, many of you won't remember that either.