KANTOREK: Some of you may have ambitions. I know of one young man who has great promise as a writer. He has written the first act of a tragedy which would be a credit to one of the masters. And he is dreaming, I suppose, of following in the footsteps of Goethe and Schiller, and I hope he will. But now our country calls. The fatherland needs leaders. Personal ambition must be thrown aside in the one great sacrifice for our country.
The message here is pretty clear: individuality is well and good, but when your country calls, your personal needs must be cast aside. When Paul decides to enlist, he puts a pin in his future plans. The tragedy of Paul's life will "follow in the footsteps of Goethe and Schiller," though we're guessing he would rather have written it than lived it.
PETER: I'm gonna get in the cavalry and ride.
MUELLER: No cavalry for me. Infantry's where you see the fighting.
PETER: Where are all the guns? That's what I want to know.
Immediately after joining the army, the young men develop new hopes and dreams, all centered on the glory and heroism they perceive will be theirs in the service. The tragedy is these dreams might come true.
HIMMELSTOSS: You're going to be soldiers, and that's all! I'll take the mother's milk out of you. I'll make you hard-boiled. I'll make soldiers out of you or kill you! Now, salute!
Here, we see a variety of young men, each with different skills, ambitions, and desires. Paul wants to be a writer; Kemmerick, we later learn, wants to be a forest ranger. But war has no use for individual skills or wants. It needs soldiers trained to kill other soldiers. So you can be all you want to be, assuming that's what you want to be.
KEMMERICK: Oh, I know what you mean! I know! I know now! They've cut my leg off. Why didn't they tell me? Why didn't they tell me?
PAUL: Franz! Franz!
KEMMERICK: …they tell me. Now I can't walk anymore!
PAUL: Franz, you must be thankful that you've come off with only that.
KEMMERICK: I wanted to be a forester once.
Kemmerick sacrifices his dreams for the war effort. Far from being ecstatic at dying for his country—as Kantorek's speech suggested—we see a young man broken and disillusioned moments before his death.
MUELLER: I've got it, Kat. Listen, "The sum of an arithmetic series is S = A + L XN over 2." Interesting, isn't it?
KAT: What do you want to learn that stuff for? One day you'll stop a bullet and it'll all be wasted.
MUELLER: I get a lot of fun out of it.
Kat points out a great hypocrisy in Kantorek's speech from earlier. Joining the army isn't providing Mueller with experience. Rather, any skills he wishes to foster are wasted if they won't help him stop a bullet for his country. And Kat's prediction proves true. Mueller does stop a bullet for his country later and his knowledge is wasted.
WESTHUS: We passed a cherry tree and when he saw it, he sort of went crazy. I could hardly drag him away.
DETERING: It was beautiful. I have a big orchard with cherry trees at home. And when they're in full blossom, from the hayloft it looks like one single sheet. So white.
ALBERT: Perhaps you can get leave soon.
But it's not just about young men sacrificing their dreams. Detering achieved his dream of having a wife and a farm, and he set that dream aside to fight in the war.
PAUL'S MOTHER: Good night, my son.
PAUL: Good night, mother.
PAUL: Oh, mother. Mother. You still think I'm a child. Why can't I put my head in your lap and cry?
Paul's new dream is more like an anti-dream. Rather than imagining what his future could bring, Paul's dream is now to go backward and return to when he was a child. Why? Without a future beyond fighting, he can only wish to return to when he still had dreams and plans and a lap to cry on.
PAUL: Oh, I'm no good for back there anymore, Kat. None of us are. We've been in this too long.
By the story's end, Paul's permanently shelved his dreams. The army wanted to turn him into a solider—"and that's all"—and that's exactly what he has become.