When two actors have an important dialogue, each wants to stand farther "up stage"--which is to say farther from the footlights--than the other, because the person fartherest "up stage" is most likely to dominate the scene. "It's no use", I once heard William A. Brady say to a veteran, who was rehearsing with a young woman star. "She knows the tricks as well as you do, and she'll back through the wall of the theater before she'll give you that scene!"
The position of the player being of such consequence, it will be seen at once that actors do not, as is commonly believed, roam about the stage at will. In point of fact, they are practically automata, reflecting the brain-pictures of the director and working out his scheme. It is not unusual for the man in charge of a rehearsal to instruct one of his puppets to "take six steps to the right at this speech", or to "come down stage four steps." No person in a performance ever "crosses" another person--that is, passes behind or in front of that other person--without having been told just when and how to do so. That movement which seems least premeditated often has been most carefully planned, and you may be sure that, at the performance you are witnessing, everybody on the stage knows to the fraction of a yard where he or she will be standing at a given moment. Edwin Booth's reply to a novice who inquired where he should go during a long speech--"Wherever you are I'll find you"--would not be possible from a stage director of today.
While this pre-arrangement may appear to the layman to be opposed to any semblance of life and spontanaeity, it is absolutely necessary to the giving of a smooth performance. If actors really "felt their parts" they would be about as dependable as horses that "feel their oats", and the representation in which they took part would soon become utterly chaotic. Fancy the awkwardness of Bassanio, in the trial scene of "The Merchant of Venice", looking around to find Shylock before inquiring: "Why dost thou whet thy knife so earnestly?"
Nor would this uncertainty be the worst effect of such unpreparedness. On the stage every move, every gesture means something; conveys some impression. Thus, in a dialogue in which one character is defying another, a single step backward will produce the effect of cowardice, or at least of weakness and irresolution, in the person who retreats. The whole tension of a scene may be lost if one of the parties to it so much as glances down or reaches out for some necessary article.