The author uses this tirade of Mr. White as a dramatic way of describing the setting outside the house. They are isolated, and there is only one other house in the new real estate development. This will help later on to provide an alternative to the possibility that the knocking...
The author uses this tirade of Mr. White as a dramatic way of describing the setting outside the house. They are isolated, and there is only one other house in the new real estate development. This will help later on to provide an alternative to the possibility that the knocking at the door must be Herbert come back from the dead in response to the second wish. It has been established that when a wish is granted by the possessor of the monkey's paw it can seem like a pure coincidence. It might be a pure coincidence that someone other than Herbert is knocking because he is lost out there and needs directions.
Since there are only two houses, the person doing such insistent knocking might have already tried the other house and found no one at home; so he would have to get some help at the Whites' house or else remain lost in the darkness. He could know there is someone at home at the Whites' house because he could have seen a light in the window. The author apparently inserted a description of Mrs. White standing at the bedroom window holding a lighted candle for the specific purpose of suggesting the possibility that the light might have been responsible for the loud and persistent knocking of some lost stranger.
He sat until he was chilled with the cold, glancing occasionally at the figure of the old woman peering through the window. The candle-end, which had burned below the rim of the china candlestick, was throwing pulsating shadows on the ceiling and walls, until, with a flicker larger than the rest, it expired.
In other words, the person knocking could have been the horribly mangled Herbert or it could have been some harmless wayfarer. And when Mr. White makes the third wish, which is for whoever it is to go away, it could have been Herbert going back to the grave in response to the wish, or it could have been a stranger finally giving up after doing all that pounding with no response.
The reader will never know whether the monkey's paw could really grant wishes or whether the previous owners' wishes only seemed to be granted by coincidence. After all, there were only two previous owners, so there were only six wishes made before Mr. White took possession of it from Sergeant-Major Morris. Those wishes were not described by Morris, who tells the family:
"He [the fakir] put a spell on it so that three separate men could each have three wishes from it."