Rudolf Steiner: "The next step is connected with warmth. Man's activity is to be sought in what streams out from him as inner warmth. Out of what proceeds from warmth — passions, impulses, instincts, desires, wishes, and so on — karma arises. Just as the parallel organ to the ear is the organ of speech, so the parallel organ to the warmth of the heart is the pituitary gland, the hypophysis. The heart takes up the warmth from outside, as the ear does sound. Thereby it perceives world warmth. The corresponding organ, which we must have in order to be able to produce warmth consciously, is the pituitary gland in the head, which at the present time is only at the beginning of its development. Just as one perceives with the ear and produces with the larynx, so one takes up the warmth of the world in the heart and lets it stream forth again through the pituitary gland in the brain. Once this capacity has been achieved, the heart will have become the organ it was intended to be. There is a reference to this in words from ‘Light on the Path’: ‘Before the soul can stand in the presence of the Masters, its feet must be washed in the blood of the heart.’ Then our heart's blood streams out, as today our words stream out into the world. In the future, warmth of soul will flood over mankind."