Khema Theri  was a Buddhist bhikkhuni, or nun, who was one of the top female disciples of the Lord Gautama Buddha along with Theri Uppalavanna. Khema was the daughter of the king of ancient Madra kingdom and she was a chief consort of the King Bimbisara of Magadha Kingdom. She was immensely beautiful, living a luxurious life. She was attached to her beauty and had a pride about her beauty. King Bimbisara was a faithful devotee of the Supreme Lord Buddha, Khema never visited the Lord Buddha because she knew The Lord Buddha preaches about the impermanence and uselessness of beauty. Queen Khema loved beautiful things, knowing that King Bimbisara hired some poets and let them sing, as she hears, the beauty of the monastery where The Lord Buddha was staying to convince her to visit the place. 

As Khema visited and looked around the monastery and approached the main hall The Lord Buddha was staying in, she sat behind a pillar so that The Lord Buddha would not be able to see her. With the psychic powers The Lord Buddha read her mind and saw that it was Khema's final life in the samsara. He created a vivid image of an extremely beautiful maiden,  even more beautiful than Khema, to appear fanning him by using his supernatural powers. This scene could only be seen by The Buddha and Khema. Khema, who admired beauty, was  Stunned by the beautiful  maiden. The Buddha then made the beautiful maiden age slowly from youth to middle age to old age and then to death before her eyes. Khema saw the maiden’s beautiful skin wrinkle, her hair change to gray and her face change into an ugly face, toothless and standing with sticks with shaking limbs until  the old lady fell down in faint, died and left only a pile of bones.. Seeing the image of the beautiful woman age and die, Khema realized she too must share the same fate. 

Then Khema was ready to listen to the Buddha and he then preached to her about the impermanence of beauty  and the dangers of lust and sense pleasures and requested her to give up sense pleasures which were transient until she attained arahantship. Following the attainment she received the permission from King Bimbisara to enter the Noble Order of Nuns and became a bhikkhuni

Because of her practices of wisdom and virtues many previous lives in the samsara Khema was able to penetrate the truth so quickly and she was able to be born  in the proximity of  many Supreme Buddhas and bodhisattvas and learned from them in her previous lives.  Though she had been listening to dharma for a long time, she had not entered the stream until her life as Khema because her aim was to become the foremost disciple in Great Insight and Wisdom among the nun in order of a future Buddha. 

In her final life when she was born as Khema, she was able to fulfill her wish.  The Gautama Buddha declared that she was the Chief among the wise in the order of the nuns.  

The  statement by Buddha to Khema is as follows, 

"Just as the spider follows the web of its own making, so are sentient beings that have attachment will follow the stream of defilements that are of their own making.  The wise do not have any desire or regard for sense pleasures, but cut off the stream of defilements and go forth to Nibbana”