Your eyes are probably the most sensitive optical instruments ever invented, by man or by nature.
In good light, your eyes can tell the difference between some 10 million colors! The best machines can recognize only four million.
From ten inches away, you could see an object just 4/1000 of an inch long. And in some cases, a person can see light shining through a hole only 1/6000 of an inch across!
Some people with very good vision can recognize faces from more than a mile away!