The act is committed, and the life is over. But I see a possible third meaning in "it is done," in which Decoud becomes, at the moment of his death, the only character in the novel to actually achieve his dream-ideal. The ideal of skepticism being negation rather than reform, it alone can end in triumph, though the form of that triumph is death. In a dark sense, Decoud's last line of dialogue might be saying, "the ideal is attained."

Compare the verb "stammer" with Mrs Gould's stammer of "material interest," another instance where a phrase with multiple meanings comes out through a kind of multiple vocalization.