HE IS PEACEFUL WHO IS FREE FROM ALL WORLDLY THINGS
Santa kayo santa vaco santava susamahito
Vantalokamiso bhikkhu upasanto' ti vuccati.
The bhikkhu who is calm in body, calm in speech, calm in mind,
who is well-composed, who has given up worldly things, is truly called a 'peaceful one'. 
There was a monk named Santakaya, who had been a lion in his past existence. It is said that lions usually go out in search of food and then rest for the next few days. Santakaya, having been a lion in his last existence, behaved very much like a lion. He moved about very little, his movements were slow and steady, and he was usually calm and composed. Other bhikkhus took his behaviour to be very queer and reported to the Buddha. After hearing the account given by the bhikkhus, the Buddha said, 'Bhikkhus! A bhikkhu should be calm and composed, he should behave like Santakaya.'