Because being a pupil is not a learning, it is a surrender. Until self is surrendered one cannot learn from another. So long as one holds on to self, the door is shut before all other selves, whether it is the nufs of man, animal, plant, rock, thought of anything in the heavens above or in the earth below.
All this is shut out beyond a certain point. When this nufs is restrained, all vibrations convey to the heart all that the heart needs. This is the beginning of being a pupil, yet after years of meditation and prayer, one does not always attain to the heart condition or sustain it. At the same time, pain or love or sorrow can bring it all in an instant.