Why do you think Carton sacrificed his life for Charles?
Sydney Carton changes places with Charles Darnay out of love for Lucie. When Carton and Darnay were first introduced at the scene of Darnay’s trial, the fact of the similarity of face is an important part of the story and can be seen as a foreshadow when this fact will play a major part. Carton resents Darnay because the Frenchman, while similar in appearance, is quite differenct in what they have made of their lives. Carton loves Lucie, but he knows he would not have a chance with her, even without Darnay. His life has been too ruined by drink to have made him worthy of her. He accepts the fact that Darnay is to be Lucie’s husband, even deciding to be friends with him. When he makes it clear to Lucie what his feelings are, he promises that he would do anything for her or for anyone that she loves. He has become a close friend of the family, especially to Lucie’s and Charles’s children. He sees his life as worthless, however. In his sacrifice of himself, he sees that he gains some measure of redemption, that his life has some meaning. His “prophecy” at the guillotine tells him that he will be well remembered and honored in the Darnay family.