Septimus, a veteran of World War I, suffers from shell shock and is lost within his own mind. He feels guilty even as he despises himself for being made numb by the war. His doctor has ordered Lucrezia, Septimus’s wife, to make Septimus notice things outside himself, but Septimus has removed himself from the physical world. Instead, he lives in an internal world, wherein he sees and hears things that aren’t really there and he talks to his dead friend Evans. He is sometimes overcome with the beauty in the world, but he also fears that the people in it have no capacity for honesty or kindness. Woolf intended for Clarissa to speak the sane truth and Septimus the insane truth, and indeed Septimus’s detachment enables him to judge other people more harshly than Clarissa is capable of. The world outside of Septimus is threatening, and the way Septimus sees that world offers little hope.
On the surface, Septimus seems quite dissimilar to Clarissa, but he embodies many characteristics that Clarissa shares and thinks in much the same way she does. He could almost be her double in the novel. Septimus and Clarissa both have beak-noses, love Shakespeare, and fear oppression. More important, as Clarissa’s double, Septimus offers a contrast between the conscious struggle of a working-class veteran and the blind opulence of the upper class. His troubles call into question the legitimacy of the English society he fought to preserve during the war. Because his thoughts often run parallel to Clarissa’s and echo hers in many ways, the thin line between what is considered sanity and insanity gets thinner and thinner. Septimus chooses to escape his problems by killing himself, a dramatic and tragic gesture that ultimately helps Clarissa to accept her own choices, as well as the society in which she lives.