At a rather early point in the play, Bosola asks the old lady a rather unusual question : “didst thou never study the mathematics ?” Surprising though such a question may sound, it is only one of the play’s many references to mathematics. Because Bosola is described as being given to study and contemplation, it comes as no surprise that he should repeatedly bring up the subject of geometry. Yet, contrary to what such allusions appear to suggest, The Duchess of Malfi is not a logical, well?ordered tragedy : events rarely follow each other in a straight line. More often than not, the course taken by the characters is a winding, meandering one, as they react to unforeseen circumstances. The more they talk about geometry, the less their lives display the kind of logic and coherence one usually associates with mathematics. The haphazard killing of Antonio is a case in point, but one might also mention the numerous instances of dramatic irony with which the play is peppered. In this paper, I propose to explore the tension between order and disorder which lies at the heart of the play. I will aim at showing that the play gets less and less geometrical – in the sense of well?ordered and carefully organized – and more and more arithmetical as the characters move closer and closer to the “deep pit of darkness” that is to swallow up most of them at the end of the play. Thus, “ending in a little point”, they become, quite literally, ciphers, that is to say, “a kind of nothing”.