Briony Tallis, aged 13: Cee?
Cecilia Tallis: Yes?
Briony Tallis, aged 13: Why don't you talk to Robbie anymore?
Cecilia Tallis: I do. We just move in different circles, that's all.
Leon Tallis: What do you say, Cee? Does the hot weather make you behave badly? Good heavens, you're blushing.
Cecilia Tallis: Just hot in here, that's all.
Tommy Nettle: Never trust a sailor on dry land.
Fiona Maguire: It says in the newspaper the army are making "strategic withdrawals."
Briony - 18 years old: Yes, I saw that. It's a euphemism for "retreat."
Cecilia Tallis: Come back. Come back to me.
Cecilia Tallis: My brother and I found the two of them down by the lake.
Police Inspector: You didn't see anyone else?
Cecilia Tallis: I wouldn't necessarily believe everything Briony tells you. She's rather fanciful.
Briony Tallis, aged 13: Prologue.
Briony Tallis, aged 13: This is the tale of spontaneous Arabella,.
Briony Tallis, aged 13: Who ran away with an extrinsic fellow.
Briony Tallis, aged 13: It grieved her parents to see their firstborn.
Briony Tallis, aged 13: Evanesce from her home to go to Eastbourne.
Robbie Turner: ...if all we have rests in a few moments in a library three and a half years ago, then I don't know... I don't.
Cecilia Tallis: Robbie... look at me. Look at me. Come back. Come back to me.
Tommy Nettle: Cheerio, pal.
Briony Tallis, aged 13: How can you hate plays?
Leon Tallis: Guess who we met on the way in.
Cecilia Tallis: Robbie.
Leon Tallis: Told him to join us tonight.
Cecilia Tallis: Oh, Leon, you didn't.
Briony - 18 years old: I am very, very sorry for the terrible distress that I have caused you. I am very, very sorry.
Briony Tallis, aged 13: Yes. I saw him. I saw him with my own eyes.
Answer: I think he realizes that Robbie most likely won't make it. He takes the letters so that he can get them back to his loved ones. He probably knows that there is a last goodbye to someone (his girl/his mother) in them. And, if nothing else, even if his body doesn't make it back to them, they have a piece of him to cherish.