No one can speak ill of another without making the illness his own, because the one speaking ill of others is ill himself. Thus the purification of the mind, from a moral point of view, should be learned in one’s everyday life by trying to consider things sympathetically, favorably, by looking at others as one looks at oneself, by putting oneself in their position instead of accusing others on seeing their infirmities. Souls on earth are born imperfect and show imperfection, and from this they develop naturally, coming to perfection. If all were perfect, there would have been no purpose in their creation. And manifestation has taken place so that every being here may rise from imperfection towards perfection. That is the object and joy of life, and for that this world was created. And if we expected every person to be perfect and conditions to be perfect, then there would be no joy in living and no purpose in coming here.
Purification of the mind therefore means to rid it of all undesirable impressions; not only of the shortcomings of others, but one must arrive at the stage where one forgets one’s own shortcomings. I have seen righteous people who have accused themselves of their errors until they became errors themselves. Concentrating all the time on error means engraving the error upon the mind. The best principle is to forget others and forget ourselves, and to set our minds upon accumulating all that is good and beautiful. When in this world of imperfection we seek for all that is good and beautiful, there are many chances of disappointment. But at the same time if we keep on looking for it- not looking at the dust but looking for the gold- we shall find it. And once we begin to find it we shall find more and more.
There comes a time in the life of a man when he can see some good in the worst man in the world. And when he has reached that point, though the good were covered with a thousand covers, he would put his hand on what is good, because he looks for good and attracts what is good.
Hazrat Inayat Khan ( Spiritual Dimensions of Psychology)