in a fish tank, which was smashed by a dog.
all the people with blue eyes will leave the island.
if there were only one person with blue eyes, they would know it because the other 99% would have brown eyes, and the person would leave.
if there were two people with blue eyes (a) and (b), the first might think the visitor was talking about the second person, and that only one person had blue eyes. the second person would think the same about the first person. when they see how neither of them leaves the island on the first day, they’d both realize they also have blue eyes, so they’d both 