In the following essay, Bristow illustrates the theory of how the number three is a key factor within Chekhov's play.

Even a casual reading of The Three Sisters reveals that the concept of three is somehow intertwined in the fabric of the play. And so it is. No matter what is seen or what is heard, the answer is usually three or its multiple. Let's begin with, say, the number of characters. Fourteen characters are named in the dramatis personae; there is, however, a fifteenth character Protopopov, the chairman of the District Council who never sets foot onstage, but his presence offstage touches or ensnares all members of the Prozorov family, including the three sisters, their brother Andrei, and his wife (after the first act) Natasha. Five of the fifteen are female; the remaining two thirds, male. If Protopopov, his old watchman Ferapont, and the old Prozorov...