There was once a blind man, who only knew the world by what he could hear, smell, taste or touch.
He had heard many mentions of an object called the moon; he was told that it sat in the sky glowing, changing shape and controlling the tides. But when he asked to touch it, he was told it was too far away.
“How do you know this ‘moon’ of yours exists if you can’t put your hands on it?” he asked skeptically. People assured him it was plainly visible, its actions had been reliably charted and tracked for centuries. “Well, prove it to me,” he said. So several people were brought to him assuring him that they’d seen the moon and knew it to exist. The blind man, however, was unconvinced.
“All I have is hearsay, I want solid proof that it exists!”
The blind man was told that any further proof would be virtually impossible to obtain. He scoffed.
“I think you guys are all delusional; you’re just imagining things that aren’t there, and then spreading gossip about it until other weak-minded people start to also think that it’s true. There is no such thing as a moon.”
And all that the frustrated people could do was to throw up their hands and walk away, and the blind man died without ever being convinced that there was a moon.