The _dramatis personae_ are Nimrod (bass), Abraham (tenor), Master Workman (baritone), four Angels (boys' voices), the choruses by Nimrod's followers, the People, Angels, and Demons. The overture is a confused, formless number, indicating the darkness. In the beginning there is no clear musical idea; but at last the subject assumes definite form as the dawn breaks and the Master Workman announces the sunrise and calls the People to their work, in the recitative, "Awake! ye Workers, awake!" The summons is followed by the chorus, "To work," in which the vocal part is noisy, broken, and somewhat discordant, representing the hurry and bustle of a crowd of working-men,--with which, however, the orchestra and organ build up a powerful theme. The song of the Master Workman is also interwoven, and the chorus is finally developed with great vigor and splendid dramatic effect. Nimrod now appears, and in a triumphant outburst ("Stately rises our Work on high") contemplates the monument to his greatness now approaching completion. Abraham rebukes him ("How, Mortal, canst thou reach His Presence?"). The scene at this point is full of dramatic vigor. Nimrod hurls imprecations at Abraham, followed by strongly contrasting choruses of the angry People and protecting Angels, which lead up to the mixed chorus of the People, indicating the confusion of tongues as they severally ascribe the escape of Abraham from the furnace-fire to Baal, Dagon, Ashtaroth, and Jehovah, and closing with tumultuous dissension, which is quelled by Nimrod. The effect of the Angels' voices in the hurlyburly is exceedingly beautiful, and the accompaniments, particularly those of the fire-scene, are very vivid. Nimrod's order to resume work on the tower is followed by the angelic strain, "Come on! let us down to Earth now hasten." Once more the Builders break out in their barbaric chorus, "To work," followed by the portentous outburst of the People, "How the Face of Heaven is o'ershadowed!" In a vigorous solo Abraham replies, "No! 'tis not Vapor nor Storm-clouds that gather." There is a final controversy between Abraham and Nimrod, and as the latter orders the patriarch to be thrown from the tower, the storm breaks, and amid the shrieks of the chorus ("Horror! horror") and the tremendous clangor of organ and orchestra on the theme already developed in the opening, the tower is destroyed.