“No,” said Samuel. “I read it somewhere. Theoretically, you can fit an infinite number of angels on the head of a pin.”
“That doesn’t mean that they’re actually there,” said Mr. Hume.
“No, but they might be,” said Samuel reasonably.
“Equally, they might not.”
“You can’t prove that they’re not there, though,” said Samuel.
“But you can’t prove that they are.”
Samuel thought about this for a couple of seconds, then said, “You can’t prove a negative proposition.”
“What?” asked Mr. Hume.
“You can’t prove that something doesn’t exist. You can only prove that something does exist.”
“Did you read that somewhere too?” Mr. Hume was having trouble keeping the sarcasm from his voice.
“I think so,” said Samuel, who, like most honest, straightforward people, had trouble recognizing sarcasm. “But it’s true, isn’t it?”
“I suppose so,” said Mr. Hume. He realized that he sounded distinctly sulky, so he coughed, then said with more force, “Yes, I suppose you’re right.”
Samuel continued. “Which means that I have as much chance of proving that there are angels on the head of this pin as you have of proving that there aren’t.”
“Are you sure you’re only eleven?”

*This is known as an inductive argument. In accordance with quantum theory, there is a probability that all possible events, no matter how strange, may occur. 

(And thank you, John Connolly, to your ridiculous references to Hume and St. Thomas Aquinas. Your books make me ponder and laugh. I think those books are the very best of all.)

Source: The Gates by John Connolly.