In Scene 1, Robert demands eggs and is upset that the Steward says the hens won't produce them until he has spoken with Joan. By the end of the scene, the hens are laying eggs again, foreshadowing the military success Joan will bring about:
STEWARD. The hens are laying like mad, sir. Five dozen eggs!
ROBERT [stiffens convulsively: crosses himself: and forms with his pale lips the words]. Christ in heaven! [Aloud but breathless]. She did come from God.
As with many other symbolic moments in the play, Shaw is having fun. The fight over the eggs is comical, and the idea that the hens are now laying eggs so rapidly is just as funny. At the same time, eggs represent fertility. In Christianity in particular, they are associated with Easter and Christ's resurrection. When Robert crosses himself and whispers "Christ in heaven," he makes sure the audience draws this connection. By simply agreeing to work with Joan, he has brought on such a bounty of eggs that he won't even know what to do with them. He sees right away that Joan will bring about an extraordinarily fertile future for France and will bring the forces back from the brink of defeat.
In addition to France's future, the eggs foreshadow Joan's future. Like Christ, she will die on a cross for the religious beliefs she tries to spread. It will take until Shaw's lifetime for her to be canonized, but when the Church finally does make her a saint, it is as though she is resurrected and turned into a flawless divine being. Shaw likes the idea of Joan, but he likes the idea of her as a flawed human. He objects to the way she is often portrayed as a larger-than-life figure who was victimized by demonic enemies, and part of his aim with this play is to humanize her and her antagonists. By using the slightly silly symbol of the eggs to foreshadow what happens to her in the far future, Shaw invites the audience to stop taking everyone in this story so seriously.
