The eye of a needle is a biblical reference which I think was made by Jesus.  I am not a biblical scholar, but I did go to Sunday School.  The eye of a needle is basically a cattle guard.  It is a gate to a city or other structure which is so small that a camel can't enter the city.  As a kid I had a hard time forming a mental picture of a camel going through the eye of a sewing needle.  Later as an adult I learned that the eye of a needle referred to a gate.