In the Autobiography of Joseph Jefferson, that humorous and human and instructive book, there is a passage that illustrates admirably the bearing of this same principle of economy of attention upon the actor’s art.  In speaking of the joint performances of his half-brother, Charles Burke, and the famous actor-manager, William E. Burton, Jefferson says: 

It was a rare treat to see Burton and Burke in the same play:  they acted into each other’s hands with the most perfect skill; there was no striving to outdo each other.  If the scene required that for a time one should be prominent, the other would become the background of the picture, and so strengthen the general effect; by this method they produced a perfectly harmonious work.  For instance, Burke would remain in repose, attentively listening while Burton was delivering some humorous speech.  This would naturally act as a spell upon the audience, who became by this treatment absorbed in what Burton was saying, and having got the full force of the effect, they would burst forth in laughter or applause; then, by one accord, they became silent, intently listening to Burke’s reply, which Burton was now strengthening by the same repose and attention.  I have never seen this element in acting carried so far, or accomplished with such admirable results, not even upon the French stage, and I am convinced that the importance of it in reaching the best dramatic effects cannot be too highly estimated.  It was this characteristic feature of the acting of these two great artists that always set the audience wondering which was the better.  The truth is there was no “better” about the matter.  They were not horses running a race, but artists painting a picture; it was not in their minds which should win, but how they could, by their joint efforts, produce a perfect work.

I am afraid that this excellent method of team play is more honored in the breach than in the observance among many of our eminent actors of the present time.  When Richard Mansfield played the part of Brutus, he destroyed the nice balance of the quarrel scene with Cassius by attracting all of the attention of the audience to himself, whereas a right reading of the scene would demand a constant shifting of attention from one hero to the other.  When Joseph Haworth spoke the great speech of Cassius beginning, “Come, Antony, and young Octavius, come!”, he was shrouded in the shadow of the tent, while the lime-light fell full upon the form of Brutus.  This arrangement so distracted the audience from the true dramatic value of the scene that neither Mansfield’s heroic carriage, nor his eye like Mars to threaten and command, nor the titanic resonance of his ventriloquial utterance, could atone for the mischief that was done.