From A Course In Miracles:
The choice to judge rather than to know is the cause of the loss of peace. Judgment is the process on which perception but not knowledge rests. I have discussed this before in terms of the selectivity of perception, pointing out that evaluation is its obvious prerequisite. Judgment always involves rejection. It never emphasizes only the positive aspects of what is judged, whether in you or in others. What has been perceived and rejected, or judged and found wanting, remains in your mind because it has been perceived. One of the illusions from which you suffer is the belief that what you judged against has no effect. This cannot be true unless you also believe that what you judged against does not exist. You evidently do not believe this, or you would not have judged against it. In the end it does not matter whether your judgment is right or wrong. Either way you are placing your belief in the unreal. This cannot be avoided in any type of judgment, because it implies the belief that reality is yours to select from.
You have no idea of the tremendous release and deep peace that comes from meeting yourself and your brothers [defined as all human spirits] totally without judgment. When you recognize what you are and what your brothers are, you will realize that judging them in any way is without meaning. In fact, their meaning is lost to you precisely because you are judging them. All uncertainty comes from the belief that you are under the coercion of judgment. You do not need judgment to organize your life, and you certainly do not need it to organize yourself. In the presence of knowledge all judgment is automatically suspended, and this is the process that enables recognition to replace perception.
You are very fearful of everything you have perceived but have refused to accept. You believe that, because you have refused to accept it, you have lost control over it. This is why you see it in nightmares, or in pleasant disguises in what seem to be your happier dreams. Nothing that you have refused to accept can be brought into awareness. It is not dangerous in itself, but you have made it seem dangerous to you.
When you feel tired, it is because you have judged yourself as capable of being tired. When you laugh at someone, it is because you have judged him as unworthy. When you laugh at yourself you must laugh at others, if only because you cannot tolerate the idea of being more unworthy than they are. All this makes you feel tired because it is essentially disheartening. You are not really capable of being tired, but you are very capable of wearying yourself. The strain of constant judgment is virtually intolerable. It is curious that an ability so debilitating would be so deeply cherished. Yet if you wish to be the author of reality, you will insist on holding on to judgment. You will also regard judgment with fear, believing that it will someday be used against you. This belief can exist only to the extent that you believe in the efficacy of judgment as a weapon of defense for your own authority.