There is an old Japanese story about a monk and a samurai. 

One day, a Zen monk was going from temple to temple, following the shaded path along a babbling brook, when he fell upon a bedraggled and badly bruised samurai.

‘Whatever happened to you?’ asked the monk.

‘We were conveying our lord’s treasure when we were set upon by bandits. But I played dead and was the only one of my company to survive. As I lay on the ground with my eyes shut, a question kept turning in my mind. Tell me, little monk, what is the difference between heaven and hell?’

‘What samurai plays dead while his companions are slain! Shame on you! You ought to have fought to the death. Look at the sight of you, a disgrace to your class, your master, and every one of your ancestors. You are not worthy of the food that you eat or the air that you breathe, let alone of my hard-won wisdom!’

At all this, the samurai puffed up with rage and appeared to double in size as he drew out his sword, swung it over his head, and brought it down onto the monk.

But just before being struck, the monk changed his tone and composure, and calmly said, ‘This is hell.’

The samurai dropped his sword. Filled with shame and remorse, he fell to his knees with a clatter of armour: ‘Thank you for risking your life simply to teach a stranger a lesson’ he said, his eyes wet with tears. ‘Please, if you could, forgive me for threatening you.’

‘And that’ said the monk, ‘is heaven.’

Neel Burton is author of Heaven and Hell: The Psychology of the Emotions