There are some great optical illusions here. I used quite a few of them when I was teaching A-level physics. It's a great reminder that we actually do a lot of processing between our eyes and the bit of the brain that thinks it's seeing.
In this image, squares A and B are actually the same colour; our brain just processes them differently - it often took using a computer graphics program to move them next to each other to convince people it really worked.
This image is actually static. Lots of people see that it's moving, and which bits are moving keeps changing. It's actually because of how our eyes focus - the bits at the edge aren't in exactly the right position, and also our eyes tend to be drawn to movement, which means that when we focus on one bit, the other bits look like they move as which bit of our eye we are using to focus on them changes.
From a spiritual point of view, they are also great reminders that what we see isn't the ultimate level of reality, because Jesus has been raised from the dead, which means that the "real us" is who we will be one day when we too have been raised from the dead, which changes our perspective on suffering in this life and so on.
For our light and momentary troubles are achieving for us an eternal glory that far outweighs them all. So we fix our eyes not on what is seen, but on what is unseen. For what is seen is temporary, but what is unseen is eternal.
Now we know that if the earthly tent we live in is destroyed, we have a building from God, an eternal house in heaven, not built by human hands. Meanwhile we groan, longing to be clothed with our heavenly dwelling, because when we are clothed, we will not be found naked. For while we are in this tent, we groan and are burdened, because we do not wish to be unclothed but to be clothed with our heavenly dwelling, so that what is mortal may be swallowed up by life. Now it is God who has made us for this very purpose and has given us the Spirit as a deposit, guaranteeing what is to come.
Therefore we are always confident and know that as long as we are at home in the body we are away from the Lord. We live by faith, not by sight.
2 Corinthians 4:17-5:7, NIV