Boa constrictor who has swallowed an elephant

[injunjane]

For the narrator in St. Exupery's Le Petit Prince the mentioned image with something of a weird shape was a test if it's worth to communicate with a 'test subject' on a deeply personal level or not.

But all the people except The Little Prince were seeing a hat instead of a giant snake who has swallowed an elephant.

For me such test (since the time I was a kid) was this book written way before I was even born:

https://en.wikipedia.org/wiki/The_Chrysalids

Not a single person has passed yet - although one French individual really tried and almost got it.