Enthusiasm as a possession by a god. The human functions as the medium for communication (for the god wants to communicate something).

Ecstasy and possession (enthusiasm) as being the same.

The entire chapter is a mix of overlapping sentimentalism and gothic elements in the form of religious enthusiasm: devoted and passionately religious Wieland is convinced by a hallucination that he must sacrifice his wife - and later children - to rid himself of mortal impurities, selfishness, and to prove his faith to God by it. The darkness and the torturous thoughts about death and murdering what's most precious to him are gothic elements. I think the cause - the hallucination itself - as godly as it looks is controversially gothic because it is a coverage of the madness and the horrors that will happen. The emotions are overpouring with grief, hesitation, and the urge to fulfill a "divine duty". The reasoning is far from prudent, although there are episodes where Wieland is torn between his love for his family and God. The inner conflict - although more exaggerated here - reminds me a little of "Contemplations", but unlike in Contemplations, where from the gloomy thoughts we reach peace, Weiland is "dancing with madness" in his inner battle, episodically going back and forth even after the deed is done - at first he's relieved even happy that he was able to obey a divine command and set himself free, but then he breaks down under its weight, and again his hallucinations bring him back to carry on and repeat it with his children too.