An explination?

Edmund Kean made his debut at the age of six-and-a-half, where he played a goblin in Drury Lane's production of Macbeth starring, of course, Mrs. Siddons as Lady Macbeth. Her brother, John Phillip Kemble, took the titular role.

During the witches' incantation scene at the beginning of Act IV, he and a number of other goblins were suppsoed to run out onstage and cluster around the mouth of the cave. Kean arrived last and had difficulty stopping; he ran into another goblin and everyone tumbled down in a domino effect.

The scene was, predictably, ruined.

Christian Bale wasn't the first to do it....

Edmund Kean rose to great popularity as an actor at the beginning of the 19th century, where his imperfect but impassioned performances fit into the new, Romantic sensibility. He and John Phillip Kemble, who represented the more classical school of acting and was famous not only for his talent but for the lengthy pauses he took between each word, shared a sort of cordial enemity that delighted newspapers.

Though Kemble was reserved and dignified, and probably treated Kean with a chilly gravity, Kean had a fierce temper. One evening, he played Othello with such passion, an admirer told him, "I really thoguht that you would have choked Iago, Mr. Kean! You seemed so tremendously in earnest."

Kean turned to his admirer in amazement and said, "In earnest! I should think so! Hang the fellow, he was trying to keep me out of focus."