Set right center.

Another time, Bhagavan residing in Savatthi, at Jetavana, taught the brethren: For example, brethren, of wheat stubble or beard of barley to be put in the wrong direction, the pressure on the arm or leg, there can pierce hands or feet, or can shed blood; the situation does not happen. 
One time, Bhagavan residing in Savatthi, at Jetavana, brethren taught: 
For example, brethren, of wheat stubble or beard of barley to be put in the wrong direction, while pressure on the arms or legs, can pierce hands or feet, or can shed blood; the situation is not happening. Wherefore? Brethren, because the antennae are placed in the wrong direction. Likewise, brethren, your brethren were centered in the wrong direction, can pierce ignorance, makes intelligent arise, can attain Nirvana;the situation is not happening. Wherefore? Brethren, because the heart was placed in the wrong direction. 
This, brethren, such as the beard of wheat, barley or antennae are located in the right direction, the pressure on the hands or feet, or hands can puncture feet, or can shed blood; the situation may occur.Wherefore? Brethren, because the antennae are located in the right direction. Likewise, brethren, the monks with the right mind set, could pierce ignorance, makes intelligent arise, can attain Nirvana; the situation may occur. Wherefore? Brethren, because the center is located in the right direction. 
DESK ANSWER: 
Many people think the practice is due to self-interest, in other words, cultivate the mind. But the human mind is multifaceted, "the head of the crime and also topped" should know how to cultivate your heart. In my experience Bhagavan, but is cultivating the mind, but the mind set in the right direction to be able to penetrate ignorance, insight achievements, attained Nirvana. 
One of the characteristics of the center is shifting, changing very quickly as chimpanzees volleyball spike, as galloping outside pasture. mind changes, students in each police killing na so the centripetal, keep up good mind to dwell on what is not easy. Often initially everyone diligently, cultivate enthusiasm but later on laxity, laziness and many people gradually degenerate. 
as large trees, foliage leaning toward what they saw he was sure it would fall in that direction. as the wheat stubble, located in the right direction can puncture the foot. Likewise, our heart must be in favor of new user liberated life of tranquility. our mind must be directed to the new insight can pierce ignorance. Therefore, attention must remain focused practitioner and remain in the new desire enlightenment Dharma now. 
Date today, although many practitioners but not many career achievements religion. So "put the mind in the right direction" is also one of the important issues that everyone should ponder Buddhists and adjust to escape suffering, spiritual sublimation, to achieve liberation, nirvana.END=NAM MO AMITABHA BUDDHA.( 3 TIMES ).VIETNAMESE TRANSLATE ENGLISH BY=THICH GIAC TAM.THE MIND OF ENLIGHTENMENT.VIETNAMESE BUDDHIST NUN=GOLDEN AMITABHA PURELAND=AUSTRALIA,SYDNEY.24/11/2016.