How does the author use foreshadowing in Electra?

When the messenger appears to tell of Orestes' feigned death, Clytemnestra is momentarily saved from her daughter's murderous rage, and in her salvation Hofmannsthal foreshadows the tragic irony of the play's conclusion. Electra's destiny will overcome that of her mother, as it has in this scene, but Electra will be deprived then, as she is now, of joining in the final act.