Iolanta – Pyotr Ilyich Tchaikovsky's last opera – was written two years before the composer’s death. In 1884 Tchaikovsky read the one-act play King Rene’s Daughter by the Danish dramatist Henrik Hertz. The poetic story of Iolanta who has been blind from birth and is cured of her ailment through love inspired Tchaikovsky, who was looking for a subject for a short, lyrical opera.
The eternal gloom in which Iolanta lives peacefully becomes a symbol of spiritual blindness and the source of deep pain for those close to her. Love ignites her heart’s desire to see the world and inspires her courage to undergo the pain that will enable her to see.
At the request of the composer, his brother Modest Ilyich Tchaikovsky wrote an operatic libretto after the plot of King Rene’s Daughter. The opera was written between July and December 1891, and the premiere took place at the Mariinsky Theatre on 6 December 1892.
It is believed that the composer’s philosophical intentions are reflected in the plot of the opera, as he had a keen interest in the philosophy of Spinoza. Whether that is the case or not Iolanta stands apart from Tchaikovsky’s other works because of its unusual "otherworldly" plot and the touching, light and serene music.

Libretto by Modest Tchaikovsky after the play Kong Renés datterby Henrik Hertz 

Act I

Southern France, Provence. Iolanta, blind from birth, is the only daughter of King René. She is the fiancée of Robert, Duke of Burgundy. Iolanta’s father hopes to have his daughter cured by the time of the wedding and it has been announced that Iolanta is being educated in a Spanish nunnery.

René doesn’t want his daughter to know about her ailment. He’s forbidden to make any mentions of the light, colours, sights: she shouldn’t know about her blindness. Everybody is kind and tender to Iolanta but she’s been inexplicably sad lately.

Ibn-Hakia, a famous Moorish physician, has been invited to the castle. He states that Iolanta can be cured but only in case she is informed of her blindness and has a desire to see. The king refuses the treatment, fearing for Iolanta’s happiness.

Act II

Two friends, knight Vaudémont and count Robert have lost their way and suddenly come to the King René’s castle. Robert announces to Vaudémont his love to beautiful Mathilde, countess of Lorraine. But since childhood he’s been engaged to Iolanta, King René’s daughter.

Vaudémont encounters Iolanta who is asleep. Stunned by her beauty he falls in love.

Iolanta hears the voices and wakes up: they rarely have guests in the castle. The young men explain that they have come here by chance. Robert leaves to find his people, Iolanta and Vaudémont stay alone. He confesses his sudden love to her.

He discovers Iolanta’s blindness and her ignorance of the fact and explains light and color to her. The couple is discovered by the king, the physician and Iolanta’s friends. They find out that the secret has been revealed to the girl. The king is desperate, Ibn-Hakia, however, is sure that it’ll save Iolanta.

Iolanta can’t wish to see, as she doesn’t know what it is. The king threatens to kill Vaudémont if the physician’s treatment fails. Iolanta is ready to do anything to save the knight. Vaudémont asks the King to marry his daughter who refuses as his daughter has been engaged since her childhood.

Robert returns to find out that Vaudémont’s beloved girl is his fiancée. Vaudémont begs Robert to admit his love to Mathilde. The king cancels the wedding contract. Ibn-Hakia takes off a bandage from Iolanta’s eyes: she can see now. She’s frightened, she can’t recognize anybody. King René comforts Iolanta and offers her a reliable partner: Vaudémont who pledges fidelity to Iolanta. Everybody glorifies God.