I gave a sermon once with a large 3D image that , when looked at properly and with parallel viewing skills (go learn ye what that meaneth) one would see the hidden picture embedded in the pattern.
The point was, of course, just how difficult it can be at times to see that which is clearly there if we just know how to do it. Once you could see the image, you could never unsee it. If you could not see it, try as you might or would not see it because one believes it's not there to see, you never saw it.
(Flippant know it all who states the momentary obvious and isn't about to try to see anything differently or ask how to"
"I think I see it"
(Wanted to but I doubt ever did)
"Yeah I see it it. So what"
(Maybe saw it. Maybe not. Can't admit to learning anything they didn't come up with or not actually seeing it, who cares.)
"C'mon! Let's go to lunch!"
(More hungry than inquisitive. Or just can't see it and gave up)