There was once a king who had an only son, called Prince Slugobyl. Now this young prince loved nothing better than travelling; so fond of it was he that when he was  twenty years old he gave his father no rest until he allowed him to go on a long journey, in short, to travel all over the world. Thus he hoped to see many beautiful and strange things, to meet with marvellous adventures, to gain happiness, knowledge, and wisdom, and to return a better man in every way than when he left. Fearing his youth and want of experience might lead him astray, his father sent with him a valued and faithful servant. When all was ready, Slugobyl bade the king adieu and set off to visit the land of his dreams.
 
As he was jogging along, allowing his horse to go at its own pace, he saw a beautiful white swan pursued by an eagle about to pounce down upon it. Seizing his crossbow, he took such good aim that the eagle fell dead at his feet. The rescued swan stopped in its flight, and turning round said to him, “Valiant Prince Slugobyl, it is not a mere swan who thanks you for your most timely help, but the daughter of the Invisible Knight, who, to escape the pursuit of the giant Kostey, has changed herself into a swan. My father will gladly be of service to you in return for this kindness to me. When in need of his help, you only have to say three times, ‘Invisible Knight, come to me.’”
 
Having thus spoken the swan flew away. The prince looked after her for a long time, and then continued his journey. He travelled on and on and on, over high mountains, through dark forests, across barren deserts, and so to the middle of a vast plain where every green thing had been burnt up by the rays of the sun. Not a single tree, not even a bush or a plant of any kind was to be seen. No bird was heard to sing, no insect to hum, no breath of air to stir the stillness of this land of desolation. Having ridden for some hours, the prince  began to suffer terribly from thirst; so, sending his servant in one direction, he himself went in another, in search of some well or spring. They soon found a well full of cool fresh water, but unluckily without either rope or bucket to draw it up. After a few moments’ thought the prince said to his servant, “Take the leathern strap used for tethering our horses, put it round your body, and I will then let you down into the well; I cannot endure this thirst any longer.”
 
“Your highness,” answered the servant, “I am heavier than you, and you are not as strong as I, so you will not be able to pull me out of the water. If you, therefore, will go down first, I shall be able to pull you up when you have quenched your thirst.”
 
The prince took his advice, and fastening an end of the strap under his arms, was lowered into the well. When he had enjoyed a deep draught of the clear water and filled a bottle of the same for his servant, he gave the signal that he wished to be pulled up. But instead of obeying the servant said, “Listen, prince; from the day you were born up to the present moment you have never known anything but luxury, pleasure, and happiness, while I have suffered poverty and slaved all my life. Now we will change places, and you shall be my servant. If you refuse you had better make your peace with God, for I shall drown you.”
 
“Stop, faithful servant,” cried the prince, “you will not be so wicked as to do that. What good will it do you? You will never be so happy as you have been with me, and you know what dreadful tortures are in store for murderers in the other world; their hands are plunged into  boiling pitch, their shoulders bruised with blows from red-hot iron clubs, and their necks sawn with wooden saws.”
 
“You may cut and saw me as much as you like in the other world,” said the servant, “but I shall drown you in this.” And he began to let the strap slide through his fingers.
 
“Very well,” said the prince, “I agree to accept your terms. You shall be the prince and I will be your servant, I give you my word.”
 
“I have no faith in words that are carried away by the first wind that blows. Swear to confirm your promise in writing.”
 
“I swear.”
 
The servant then let down paper and pencil, and dictated the following:
 
“I hereby declare that I renounce my name and rights in favour of the bearer of this writing, and that I acknowledge him to be my prince, and that I am his servant. Written in the well.
(Signed) Prince Slugobyl.”
 
The man having taken this document, which he was quite unable to read, drew out the prince, took off the clothes in which he was dressed, and made him wear those he himself had just taken off. Thus disguised they travelled for a week, and arriving at a large city, went straight to the king’s palace. There the false prince dismissed his pretended servant to the stables, and presenting himself before the king, addressed him thus in a very haughty manner:
 
“King, I am come to demand the hand of your wise and beautiful daughter, whose fame has reached my father’s court. In exchange I offer our alliance, and in case of refusal, war.”
 
  
“Prayers and threats are equally out of place,” answered the  king; “nevertheless, prince, as proof of the esteem in which I hold the king, your father, I grant your request: but only on one condition, that you deliver us from a large army that now besets our town. Do this, and my daughter shall be yours.”
 
“Certainly,” said the impostor, “I can soon get rid of them, however near they may be. I undertake by to-morrow morning to have freed the land entirely of them.”
 
In the evening he went to the stables, and calling his pretended servant, saluted him respectfully and said, “Listen, my dear friend, I want you to go immediately outside the town and destroy the besieging army that surrounds it. But do it in such a way that every one will believe that I have done it. In exchange for this favour I promise to return the writing in which you renounced your title of prince and engaged to serve me.”
 
The prince put on his armour, mounted his horse, and rode outside the city gates. There he stopped and called three times to the Invisible Knight.
 
“Behold me, prince, at your service,” said a voice close to him. “I will do anything you wish, for you saved my only daughter from the hands of the giant Kostey; I shall always be grateful.”
 
Slugobyl showed him the army he had to destroy before morning, and the Invisible Knight whistled and sang:
 
“Magu, Horse with Golden Mane,
 
I want your help yet once again,
 
Walk not the earth but fly through space
 
As lightnings flash or thunders race.
 
Swift as the arrow from the bow,
 
Come quick, yet so that none can know.”
 
 At that instant a magnificent grey horse appeared out of a whirlwind of smoke, and from his head there hung a golden mane. Swift as the wind was he, flames of fire blazed forth from his nostrils, lightnings flashed from his eyes, and volumes of smoke came from his ears. The Invisible Knight leapt upon his back, saying to the prince, “Take my sword and destroy the left wing of the army, while I attack the right wing and the centre.”
 
The two heroes rushed forward and attacked the invaders with such fury that on all sides men fell like chopped wood or dried grass. A frightful massacre followed, but it was in vain that the enemy fled, for the two knights seemed to be everywhere. Within a short time only the dead and dying remained on the battle-field, and the two conquerors quietly returned to the town. On reaching the palace steps, the Invisible Knight melted into the morning mist, and the serving-man prince returned to the stables.
 
That same night it happened that the king’s daughter, not being able to sleep, had remained on her balcony and seen and heard all that had taken place. She had overheard the conversation between the impostor and the real prince, had seen the latter call to his assistance the Invisible Knight, and then doff his royal armour in favour of the false prince; she had seen and understood everything, but she determined to keep silence for a little longer.
 
But when on the next day the king, her father, celebrated the victory of the false prince with great rejoicings, loaded him with honours and presents, and calling his daughter expressed a wish that she should marry him—the princess could be silent no longer. She walked up to the real prince, who  was waiting at table with the other servants, took his arm, and leading him to the king, said:
 
“Father, and all good people, this is the man who has saved our country from the enemy, and whom God has destined to be my husband. He to whom you pay these honours is but a vile impostor, who has robbed his master of name and rights. Last night I witnessed such deeds as eye has never seen nor ear heard, but which shall be told afterwards. Bid this traitor show the writing which proves the truth of what I say.”
 
When the false prince had delivered up the paper signed by the serving-man prince, it was found to contain the following words:
 
“The bearer of this document, the false and wicked servant of the serving-man prince, shall receive the punishment his sin deserves.
(Signed) Prince Slugobyl.”
 
“What? Is that the real meaning of that writing?” asked the traitor, who could not read.
 
“Most assuredly,” was the reply.
 
Then he threw himself at the king’s feet and begged for mercy. But he received his punishment, for he was tied to the tails of four wild horses and torn to pieces.
 
Prince Slugobyl married the princess. It was a magnificent wedding. I myself was there, and drank of the mead and wine; but they only touched my beard, they did not enter my mouth.