As a point of reference, the thread a camel through the eye of a needle refers to the small entrance doors located in the walls of old cities, like Jerusalem. These doors were the only entrance points at night, once the main gate entry was secured. While very difficult to get a camel to go down on its knees and crawl through the doors (a.k.a - Needles), it was possible. The doors/needles height was low to prevent raiders from easily invading.