'If at any time, in the days that are to come,' she said, 'you upbraid me, promise that this you will never do while we are sailing or while we are near to sea or lake or tiny rivulet. For should one of my race hear you use harsh words toward me, then would they regain their power, and snatch me away from you for ever. Then would I be forced to dwell all the rest of my life in the crystal palace below the blue sea. Nor could I ever come up to you unless, indeed, I was sent by my kindred, when alas! only great sadness would befall us both. Promise me, therefore, that when we are near water, you will remember what I have now told you.'
Huldbrand promised, and hand in hand they went in search of Bertalda.
She meanwhile had called together some workmen, and as she saw the knight and Undine drawing near, she gave her orders to the men in a loud, discontented voice. 'The stone may now be removed. Hasten, see that it be done immediately!'
But the knight was angry with the maiden for daring thus to give what orders she pleased, and he shouted at once, so that the workmen might hear, 'The stone shall stay where it is! It shall not be removed!'
And the men went away, well pleased that they need not undo what their gentle mistress had ordered to be done.
Huldbrand then reproved Bertalda for her rude behaviour to his wife, but she scarcely heard his words, as she turned away in anger and hastened to her room.
Soon supper was placed on the table, but Huldbrand and Undine waited in vain for Bertalda. At length they sent a servant to call her, but the maid came back only to tell them that she was nowhere to be found. In her room, however, a letter had been left addressed to the knight. Huldbrand opened it hastily and read:-'Forgive me, Sir Knight, that I have forgotten that I am only a poor fisher-girl. I will go to my father's miserable cottage, where I cannot well commit the same fault again. Fare you well, you and your beautiful wife.'
'You must go without delay to seek her and bring her back,' said Undine.
And Huldbrand did not need to be urged. Already he had ordered his horse to be saddled that he might ride after the maiden.
In vain he asked the servants in what direction Bertalda had gone. No one had seen her. It was only as the knight impatiently mounted his steed, that a page ran up to him crying, 'The lady Bertalda rode toward the Black Valley.'