Significant quotes from Shelley's apocalyptic novel The Last Man would be those that address the central thematic ideas of the novel. One of these is the nature of humanity. Shelley introduces this idea early in volume 1, chapter 2:
What is there in our nature that is for ever urging us on towards pain and misery?
This quote comes in a passage of the chapter in which Lionel, the narrator, describes the love affair between his former enemy—and current best friend—Adrian (the son of the deceased monarch of England) and a young Greek woman named Evadne. Lionel has heretofore described Adrian's heroic, deeply admirable nature; he is disgusted that Evadne seems only to be leading Adrian on and not returning the abiding love he feels for her.
In this context, the quote above suggests that people often make wrong choices when they are led by their hearts. The noble Adrian unwittingly sets himself up to experience pain and misery because he has chosen an unworthy recipient of his love. Interpreted more broadly, Lionel ruminates on the inability of man to foresee the consequences of his actions, which seem to inevitably lead to suffering.
Shelley further explores this idea in volume 2, chapter 4:
Let us live for each other and for happiness; let us seek peace in our dear home, near the inland murmur of streams, and the gracious waving of trees, the beauteous vesture of earth, and sublime pageantry of the skies. Let us leave "life," that we may live.
This quote describes Lionel's feelings after he and Adrian travel to Greece. The tragic events that he witnesses in Greece—Raymond's death and Perdita's suicide—leave Lionel cynical and afraid of the world. He believes that a life of quiet isolation and comfort in England will bring him peace and happiness. Life has become the "labyrinth of evil" he wishes to avoid, yet the impending conclusions of the novel demonstrate Lionel's naivete.
The world eventually finds itself a direct force in Lionel's life, forcing him out of voluntary isolation with friends to total isolation when he becomes the (literal) last man. Shelley, then, criticizes the idea that people can escape the challenges of life simply by ignoring them.
A final important quote from the novel comes in its final chapter,...
(The entire section is 586 words.)