" The motor isolation is meant to ensure an interruption of the connection in thought. The normal phenomenon of concentration provides a pretext for this kind of neurotic procedure: what seems to us important in the way of an impression or a piece of work must not be interfered with by the simultaneous claims of any other mental processes or activities. But even a normal person uses concentration to keep away not only what is irrelevant or unimportant, but, above all, what is unsuitable because it is contradictory. He is most disturbed by those elements which once belonged together but which have been torn apart in the course of his development—as, for instance, by manifestations of the ambivalence of his father-complex in his relation to God, or by impulses attached to his excretory organs in his emotions of love. Thus, in the normal course of things, the ego has a great deal of isolating work to do in its function of directing the current of thought. And, as we know, we are obliged, in carrying out our analytic technique, to train it to relinquish that function for the time being, eminently justified as it usually is. "
― Sigmund Freud , Inhibitions, Symptoms and Anxiety