You took the words out of my mouth, also, if you wish to debate this topic, please take the time to print the image and you will see that the illusion persists. It points out basic flaws in the human eye, as does the 2nd link. I can provide dozens more, all of which point out how easily fooled the human eye is.
This question for for FE'rs (well, people who present themselves as believing in a FE)
If you were standing in a soccer field, and there were 2 stakes in the ground 40 feet apart, and you were standing between them. Do you think you could place a 3rd stake in line between the first 2 stakes using your human eye, lining yourself up with them...
(this is first week surveying, for those that are keeping score at home)