They come to the Tree of Human Knowledge on the banks of the Styx and Faust picks the fruit.
From this detail it is easy to imagine that the libretto is bizarre.
The authorship of this amazing libretto is unknown, but it is not strange that Meyerbeer soon abandoned it.

From this still-born _Faust_, Scribe, at the request of the author, constructed _Robert le Diable_.

An aria sung by Faust on the banks of the Styx becomes the _Valse Infernale_.
The necessity of utilizing pre-existing fragments explains some of the incoherence of this incomprehensible piece.

It also explains the creation of Bertram, half man, half devil, who was invented as a substitute for Mephistopheles.

The fruit of the Tree of Human Knowledge became the _Rameau Veneree_ in the third act, and the beautiful religious scene in the fifth act, which has no relation to the action, is a transposition of the Easter scene.
So Scribe should not be blamed for making a poor piece when he had so many difficulties to contend with.