I remember fondly an old children's story called The Blind Men and the Elephant. This profound yet simple story is a great illustration of the limitations of human perception.
One version of the story describes six blind men living in a village. One day, a caravan of travelers came bringing an elephant. The blind men had no idea what an elephant was, and together they went to "see" it for themselves! Each of them unknowingly inspected by touch only part of the elephant and then reported his conclusion to the other men.