Essential Tibetan Buddhism, compiled and translated by Robert Thurman, Castle Books, p.99

When Atisha arrived in Tibet, his three disciples, Ku, Ngog, and Brom, asked him, "To attain the high state of liberation and omniscience, which is the more important to follow, the precept of the lama, or the scriptures and commentaries?

Atisha replied, "The precept of the lama is more important than the scriptures and commentaries."

"Why?" They asked.

"If you know that emptiness is the prime characteristic of all things, and even if you can recite the entire canon by heart, if, at the time of practice you do not apply to yourself the precept of the lama, you and the dharma will go separate ways."

They asked, "Please define the practice and the precept of the lama. Is it simply striving to practice mental, verbal, and physical virtuous deeds, acting in accordance with the three vows of individual liberation, Bodhisattvahood, and Tantra?"

"Both of these will be insufficient," replied Atisha.

"Why?"

"Although you keep these three vows, if you do not renounce the three realms of cyclic life, your deeds will only increase your worldliness. Although you strive day and night to commit physical, verbal, and mental virtuous acts, if you do not dedicate your efforts to universal enlightenment, you will end up with numerous wrong attitudes. Even though you meditate and come to be considered holy and a wise teacher, if you do not abandon your interest in the eight worldly concerns, whatever you do will only be for the purpose of this life, and in the future you will miss the right path."

Again they asked, "What is the highest teaching of the path?"

Atisha replied, "The highest skill lies in the realization of selflessness. The highest nobility lies in taming your own mind. The highest excellence lies in having the attitude that seeks to help others. The highest precept is continual mindfulness. The highest remedy lies in understanding the intrinsic transcendence of everything. The highest activity lies in not conforming with worldly concerns. The highest mystic realization lies in lessening and transmuting the passions. The highest charity lies in nonattachment. The highest morality lies in having a peaceful mind. The highest tolerance lies in humility. The highest effort lies in abandoning attachment to works. The highest meditation lies in the mind without claims. The highest wisdom lies in not grasping anything as being what it appears to be."

"And what is the ultimate goal of the teaching?"

"The ultimate goal of the teaching is that emptiness whose essence is compassion."