This is a twist on the old "elephant" story.
One day a teacher in a city where no one had seen an elephant (work with me) decided to take his children to see one up close and in person. So they arrived at the location and the teacher told the students that they would have to put on goggles that blinded them and that they would enter a room and in that room would be an elephant. The kids were all excited as they donned their goggles. They were all a chatter about what they would feel, smell and hear.
They were ushered into the room where the elephant was lazily sitting on the floor. The children wandered around aimlessly at first as they tried to find the elephant. Soon one stumbled across something and shouted excitedly "over here!"
Soon the children were all around the elephant.
"Oooh it's so hard and long!" said one feeling on the tusks.
"Well it's got a long nose. I can feel the air moving in and out like my nose."
One child said, "it has small ears!" as he felt the head of elephant. He felt the nose and it wasn't long. there was a bit of doubt as he had heard the other kid say the nose was long. "Must be long to him" he thought to himself as he continued to feel up the elephant.
"Man this thing has big feet!" Exclaimed another child.
The kid who had felt the small ears said to himself: "What is wrong with those kids? The feet didn't seem particularly big to me. They are such over the top. Wait until we can remove these goggles and I'm gonna make fun of them for being so dramatic."
Finally the teacher announced that the time for inspection was over and all the kids would be lead to another room where they could draw the elephant based on what they had "observed". So off they went to the next room where crayons and paper awaited them.
They all drew their pictures and though each child drew differently they all had similar characteristics. Except one. The child who had felt a small nose, small ears and small feet had drawn something entirely different than his peers.
When he presented his drawing to the teacher he said, "Here. I've drawn the elephant."
"No you did not." Said the teacher.
"Yes I did." replied the boy " I drew exactly what I remember feeling."
"I'm sure you did." said the teacher. "But that is not an elephant."
"I don't get it." said the boy. "You said we were in the room with an elephant. You said to go and inspect the elephant and I did that. This is exactly what I felt."
"Well," said the teacher, "just because I said that there was an elephant in the room doesn't mean that there was one. Nor does it mean that the elephant was the only thing in the room. You assumed you were feeling an elephant because you were lead to believe it was an elephant. You ignored the very evidence presenting itself to you that it was not an elephant. Young man, that was a bull you were feeling on."
The boy was pretty annoyed to have been fooled like that but he had learned a valuable lesson that day: Don't let your belief in elephants lead you to talk a lot of bull.