Dashing along on a black horse, Faust and Mephistopheles see a group of figures by a stone block. Neither knows what these figures are doing, exactly (at least the devil claims not to know): brewing or making something, soaring, bending and bowing, scattering things and consecrating them. Mephistopheles identifies the figures as witches and says that the two must hurry on.
The stone block is the scaffold to be used the next day for Gretchen’s execution. Mephistopheles is evasive when answering Faust’s questions about the figures on the scaffolding, so some critics think they might not be witches at all, but instead good spirits preparing to save Gretchen’s soul.