Tchaikovsky's last opera was "Iolanta" (Iolanthe) (1891) with a libretto by Modest Tchaikovsky after Henrik Hertz's play "King René's Daughter".
Iolanta, born blind, is kept unaware of her condition by father the king in order not to cause her unhappiness. Nevertheless, she has doubts expressed in a beautiful aria in the opening scene in the lush garden with hedge roses and fruit trees. A Moorish physician appears before the king saying that it is possible to give her sight but warns that Iolanta's spirit must be prepared to accept the idea of light. The knight Vaudémont falls in love with Iolanta. They converse about the color of roses and Iolanta says she does not know what he means. He explains, realizing she is blind, but she replies that she does not need light in order to praise the Creator. Iolanta agrees to the operation by the Moorish physician who says that the spiritual condition has been met. The king threatens Vaudémont with death if the operation does not work, but this is just to give Iolanta incentive. The operation is successful, Vaudémont's friend Robert is released from his childhood betrothal to Iolanta, so that the new couple are free to marry, and the opera closes with a praise to light and its Creator.