Act IV. The first scene in this act takes place in _Marguerite's

room. No wonder _Méphistophélès_ laughed when he saw her in _Faust's_ arms. She has been betrayed and deserted. The faithful _Siebel_, however, still offers her his love--"Si la bonheur à sourire t'invite" (When all was young and pleasant, May was blooming)--but _Marguerite_ still loves the man who betrayed her, and hopes against hope that he will return.

This episode is followed by the cathedral scene. _Marguerite_ has entered the edifice and knelt to pray. But, invisible to her, _Méphistophélès_ stands beside her and reminds her of her guilt. A chorus of invisible demons calls to her accusingly. _Méphistophélès_ foretells her doom. The "Dies iræ," accompanied on the organ, is heard. _Marguerite's_ voice joins with those of the worshippers. But _Méphistophélès_, when the chant is ended, calls out that for her, a lost one, there yawns the abyss. She flees in terror. This is one of the most significant episodes of the work.

Now comes a scene in the street, in front of _Marguerite's_ house. The soldiers return from war and sing their familiar chorus, "Gloire immortelle" (Glory immortal). _Valentine_, forewarned by _Siebel's_ troubled mien that all is not well with _Marguerite_, goes into the house. _Faust_ and _Méphistophélès_ come upon the scene. Facing the house, and accompanying himself on his guitar, the red gallant sings an offensive serenade. _Valentine_, aroused by the insult, which he correctly interprets as aimed at his sister, rushes out. There is a spirited trio, "Redouble, ô Dieu puissant" (Give double strength, great God on high). _Valentine_ smashes the guitar with his sword, then attacks _Faust_, whose sword-thrust, guided by _Méphistophélès_, mortally wounds _Marguerite's_ brother. _Marguerite_ comes into the street, throws herself over _Valentine's_ body. With his dying breath her brother curses her.

Sometimes the order of the scenes in this act is changed. It may open with the street scene, where the girls at the fountain hold themselves aloof from _Marguerite_. Here the brief meeting between the girl and _Siebel_ takes place. _Marguerite_ then goes into the house; the soldiers return, etc. The act then ends with the cathedral scene.