THE FULLY CONTROLLED PERSON IS CALLED A BHIKKHU
Hattha sannato pada sannato vacaya sannato sannatuttamo
Ajjhattarato samahito eko santusito tam ahu bhikkhum.
He who is controlled in hand, controlled in foot, controlled in speech, and possessing the highest control (of mind),
delighted within, composed, solitary and contented, him they call a bhikkhu. 
Once, there was a bhikkhu who was very skilful in throwing stones. He could even hit any fast-moving object. One day while sitting with another bhikkhu after having their bath in the river, he saw two geese flying over them. He told his friend that he could hit the eye of one of the geese. He took a pebble, aimed and threw it at one of the geese. The pebble struck the bird's eye. The bird cried out in pain and dropped dead at the feet of the young bhikkhu.
Other bhikkhus seeing the incident reported it to the Buddha. He admonished the young bhikkhu, 'My son, why have you killed the bird? Especially as a bhikkhu, you should be practising loving-kindness to all beings and should also be striving ardently for liberation. A bhikkhu must have control over his thoughts, words and deeds.'*
*A bhikkhu is expected to observe the four kinds of Higher Morality:
- Patimokkha Sila- The fundamental moral code.
- Indriyasamvara Sila- Morality pertaining to sense-restraint.
- Ajivaparisuddhi Sila- Morality pertaining to purity of livelihood.
- Paccayasannissita Sila- Morality pertaining to the use of necessaries of life.
These four kinds of morality are collectively known asSila Visuddhi(Purity of Virtue).