This book is truly a visual feast for the eyes, a fun book just to browse and look at or to learn about visual illusions.
The theory about how each optical illusion works can be
very simple, or very complex, sometimes requiring advanced
neurophysiology and even mathematics and calculus to understand, so
there's great variation in terms of the range of difficulty and
complexity.
Anyway the learning experiences you can get out of visual illusions are a
greater understanding - & appreciation - of how the brain really
works & its innate abilities.