Sn 2.8 Nava Sutta
Nava Sutta: The Simile of the Boat
translated from the Pali by
John D. Ireland
"He from whom a person learns the Dhamma should be venerated, as the devas venerate Inda, their Lord.  He, (a teacher) of great learning, thus venerated, will explain the Dhamma, being well-disposed towards one. Having paid attention and considered it, a wise man, practicing according to Dhamma, becomes learned, intelligent and accomplished by associating himself diligently with such a teacher.
"But by following an inferior and foolish teacher who has not gained (fine) understanding of the Dhamma and is envious of others, one will approach death without comprehending the Dhamma and unrelieved of doubt.
"If a man going down into a river, swollen and swiftly flowing, is carried away by the current how can he help others across?
"Even so, he who has not comprehended the Dhamma, has not paid attention to the meaning as expounded by the learned, being himself without knowledge and unrelieved of doubt how can he make others understand?
"But if (the man at the river) knows the method and is skilled and wise, by boarding a strong boat equipped with oars and a rudder, he can, with its help, set others across. Even so, he who is experienced and has a well-trained mind, who is learned and dependable,  clearly knowing, he can help others to understand who are willing to listen and ready to receive.
"Surely, therefore, one should associate with a good man who is wise and learned. By understanding the meaning of what one has learned and practicing accordingly one who has Dhamma-experience  attains (supreme) happiness." 
1. "Inda" (Sanskrit "Indra") is another name for Sakka, the ruler of the gods.
2. He has a character which remains unperturbed by the vicissitudes of life (Comy).
3. Possessing the supporting conditions for attaining the Paths and Fruits of stream-winning, once-returning, never-returning and Final Sainthood (arahatta).
4. One who has fully understood or experienced the Dhamma by penetrating to its essence through the practice taught by a wise teacher (Comy).
5. The transcendental happiness of the Paths and Fruits and of Nibbana.