For hundreds of years, the secret doctrines of Zen have been transmitted from master to student in the form of seemingly absurd riddles or parables called koans. Intense meditation upon these is said to lead to enlightenment. Heres one of my favorites for anyone who is interested

The Gates of Paradise

A soldier named Nobushige came to Hakuin, and asked: "Is there really a paradise and a hell?"

"Who are you?" inquired Hakuin.

"I am a samurai," the warrior replied.

"You, a soldier!" exclaimed Hakuin. "What kind of ruler would have you as his guard? Your face looks like that of a beggar."

Nobushige became so angry that he began to draw his sword, but Hakuin continued: "So you have a sword! Your weapon is probably much too dull to cut off my head."

As Nobushige drew his sword Hakuin remarked: "Here open the gates of hell!"

At these words the samurai, perceiving the master's discipline, sheathed his sword and bowed.

"Here open the gates of paradise," said Hakuin.

101 Zen Koans ~ Numbers, 56 & 57.