This is the first classic book on visual illusions by J Richard Block, the author, who also wrote a second book entitled 'Seeing Double'. Both are printed in large format. In fact, there is also a card deck which amplifies the earlier book.
Both books discussed the phenomena of human perception through hundreds of perplexing visual illusions & mind-bending eye tricks gathered from around the world.
The entire collection in the two books is definitely amazing and unique in some way.
The best learning experiences I got out of these two wonderful books are a greater understanding - & appreciation - of how the brain really works. I often use many of the visual illusions to demonstrate the principal operating principles of the brain, particularly the salient aspects of selective recognition and patterning. I have also found that some of them have been very useful in demonstrating cognitive traps & pattern interrupts, especially in the context of personal creativity.
Although the visual illusions are fun to play with, I find them very educational, just as what I have elaborated.
There is another type of visual illusions, known as random dot stereograms (some people call them 3D visual illusions), which are more fun but somewhat harder to play with. Nevertheless, they are also very educational, especially in understanding - & appreciating - how the brain really works!