We have seen what it means to purify the life of the body and of the mind; but there is a further purity which is the purity of the heart, the constant effort to keep the heart pure from all the impressions which come from without and are foreign to the true nature of the heart, which is love. And this can only be done by a continual watchfulness over one's attitude towards others; by overlooking their faults, by forgiving their shortcomings, by judging no one except oneself. For all harsh judgments and bitterness towards others are like poison; to feel them is exactly the same as absorbing poison in the blood: the result must be disease. First disease in the inner life only, but in time the disease breaks out in the physical life; and these are illnesses which cannot be cured. External cleanliness does not have much effect upon the inner purity; but inner uncleanness causes disease both inwardly and outwardly.