There are times, moreover, when it is not only permissible to suspend the tension, but when, by so doing, a great artist can produce a peculiar and admirable effect. A sudden interruption, on the very brink of a crisis, may, as it were, whet the appetite of the audience for what is to come. We see in the Porter scene in Macbeth a suspension of this nature; but Shakespeare used it sparingly, unless, indeed, we are to consider as a deliberate point of art the retardation of movement commonly observable in the fourth acts of his tragedies. Ibsen, on the other hand, deliberately employed this device on three conspicuous occasions. The entrance of Dr. Rank in the last act of A Doll’s House is a wholly unnecessary interruption to the development of the crisis between Nora and Helmer. The scene might be entirely omitted without leaving a perceptible hiatus in the action; yet who does not feel that this brief respite lends gathered impetus to the main action when it is resumed? The other instances are offered by the two apparitions of Ulric Brendel in Rosmersholm. The first occurs when Rosmer is on the very verge of his momentous confession to Kroll, the second when Rosmer and Rebecca are on the very verge of their last great resolve; and in each case we feel a distinct value (apart from the inherent quality of the Brendel scenes) in the very fact that the tension has been momentarily suspended. Such a rallentando effect is like the apparent pause in the rush of a river before it thunders over a precipice.