Let me show you another very old optical illusion. I wanted to share it with you not because of quality of illusion it holds (actually, this one’s pretty naive), but because it seems interesting when you see it from historical view. In one hand it, it may helps us understand how illusions progressed over time. On the other hand, there were even older examples with much better effect. I’m not sure I understand it fully, but the original text that came along with this print went something like this:
Were they really motor-men (smoothly propelled along the surface by an unseen force) that our poor old friend suddenly encountered in the streets of London, or were they merely two British workmen employed in digging down into the roadway taking five minutes rest in situ?