The Life of the Buddha: Incarnation of the Buddha.
When Dipankara with all his followers had passed by, Sumedha examined the Ten Perfections indispensable to Buddhahood, and determined to practise them in his future births. So it came to pass, until in the last of these births the Bodhisatta was reborn as Prince Vessantara, who exhibited the Perfection of Supernatural Generosity, and in due time passed away and dwelt in the Heaven of Delight. When the time had come for the Bodhisatta to return to earth for the last time, the deities of the ten thousand world-systems assembled together, and, approaching the Bodhisatta in the Heaven of Delight, said: "Now has the moment come, O Blessed One, for thy Buddhahood; now has the time, O Blessed One, arrived!" Then the Bodhisatta considered the time, the continent, the district, the tribe, and the mother, and, having determined these, he assented, saying: "The time has come, O Blessed Ones, for me to become a Buddha." And even as he was walking there in the Grove of Gladness he departed thence and was conceived in the womb of the lady Maha Maya.
The manner of the conception is explained as follows. At the time of the midsummer festival in Kapilavatthu, Maha Maya, the lady of Suddhodana, lay on her coach and dreamed a dream. She dreamt that the Four Guardians of the Quarters lifted her up and bore her away to the Himalayas, and there she was bathed in the Anotatta lake and lay down to rest on a heavenly couch within a golden mansion on Silver Hill. Then the Bodhisatta, who had become a beautiful white elephant, bearing in his trunk a white lotus flower, approached from the North, and seemed to touch her right side and to enter the womb. The next day when she awoke she related the dream to her lord, and it was interpreted by the Brahmans as follows: that the lady had conceived a man-child who, should he adopt the life of a householder, would become a Universal Monarch; but if he adopted the religious life he would become a Buddha, removing from the world the veils of ignorance and sin.
It should be told also that at the moment of the incarnation the heavens and the earth showed signs, the dumb spoke, the lame walked, all men began to speak kindly, musical instruments played of themselves, the earth was covered with lotus flowers, and lotuses descended from the sky, and every tree put forth its flowers. From the moment of the incarnation, moreover, four devas guarded the Bodhisatta and his mother, to shield them from all harm. The mother was not weary, and she could perceive the child in her womb as plainly as one may see the thread in a transparent gem. The Lady Maha Maya carried the Bodhisatta thus for ten lunar months; at the end of that time she expressed a wish to visit her family in Devadaha; and she set out on the journey. On the way from Kapilavatthu to Devadaha there is a pleasure-grove of Sal-trees belonging to the people of both cities, and at the time of the queen's journey it was filled with fruits and flowers. Here the queen desired to rest, and she was carried to the greatest of the Sal-trees and stood beneath it. As she raised her hand to take hold of one of its branches she knew her time had come, and so standing and holding the branch of the Sal-tree she was delivered. Four Brahma devas received the child in a golden net, and showed it to the mother, saying: "Rejoice, O Lady! a great son is born to thee." The child stood upright, and took seven strides and cried: "I am supreme in the world. This is my last birth: henceforth there shall be no more birth for me!"
At one and the same time there came into being the Seven Connatal Ones, viz., the mother of Rahula, Ananda the favourite disciple, Channa, the attendant, Kanthaka, the horse, Kaludayi, the minister, the great Bodhi tree and the vases of treasure.