There were several types of trials by fire: walking barefoot over hot coals, holding a hot piece of iron in one's hands, or wearing a shirt dipped in hot wax.
Käthchen walks in on Kunigunde during her bathing and is so shocked by what she sees that she cannot speak a word.
Kunigunde, having been discovered, decides to have Käthchen poisoned. Finally, the castle square with a view of the castle and a church Strahl confronts the emperor about the validity of Käthchen’s nobility and in a monologue of the emperor he confesses that he is her biological father.
Through questioning they discover that they have met already in their dreams.
The Count then begins to realize that Käthchen is his real prophesied wife.
Act 5 – City of Worms in a plaza in front of the imperial castle. Strahl invites Käthchen to his wedding, but in a twist she learns that it is her wedding. Kleist wrote: "The judgement of the masses has governed me too much until now; especially Käthchen von Heilbronn bears witness to that.
Shocked by this sudden turn of events, Käthchen passes out and the play ends in turmoil. From the beginning, it was a marvellous concept and only the intent to adapt it for stage play has led me to mistakes that I would now like to cry over.
In short, I want to soak up the thought that, if a work is only quite freely sprung from one human mind, then that same work must necessarily belong to the whole of mankind." "Because he who loves Käthchen cannot completely disregard Penthesilea because they belong together like the and - of algebra, and they are one and the same being, only imagined out of contrary relations." Kleist in a letter to Heinrich J. "I am now eager to learn what you would have to say about Käthchen, because she is the reverse side of Penthesilea [an Amazon-feminist heroine of an earlier play], her opposite pole, a creature as powerful through submission as Penthesilea is through action ...?
" Kleist in a letter to Marie von Kleist (late autumn 1807) The trial by fire is originally a medieval ordeal meant to test the innocence of a defendant in undecided court cases.
Throughout the monologue it becomes increasingly evident that he will never act upon these feelings, given the vast social class division.
We also learn of the Count’s enemy Kunigunde, whose impending lawsuits would take away much of Strahl’s rightful lands.
Other ordeals were also common, wherein the defendant with hands and feet bound together was thrown into water.