Quoted from the Book of Wisdom by Chan Master Wu Jue Miao Tian.
What is Heart Chan? Heart is the Buddha-nature within all of us, which we want to look inward to get in touch with moment-by-moment. Chan is the universal life force and wisdom. The core teachings of our Chan School rest in the special way of teaching without words and formalities and directly form-heart-to-heart. Nothing outside the heart has any spiritual significance-they are simply attachments. Through meditation, the heart is transformed from dark to light, from contaminated to pure, and from small to big. Any mundane matters that bother you should not be treated too seriously and personally. Do not let them contaminate your originally peaceful and pure heart.