The link of connexion between the various Bodhisats in the future Buddha's successive births is not a soul which is transferred from body to body, but the karma, or character, which each successive Bodhisat inherits from his predecessors in the long chain of existences.
As the newer school did not venture so far as to claim as Bodhisats the disciples stated in the older books to have been the contemporaries of Gotama (they being precisely the persons known as Arahats), they attempted to give the appearance of age to the Bodhisat theory by representing the Buddha as being surrounded, not only by his human companions the Arahats, but also by fabulous beings, whom they represented as the Bodhisats existing at that time.
In the opening words of each Mahayana treatise a list is given of such Bodhisats, who were beginning, together with the historical Bodhisats, to occupy a position in the Buddhist church of those times similar to that occupied by the saints in the corresponding period of the history of Christianity in the Church of Rome.
And these lists of fabulous Bodhisats have now a distinct historical importance.
Among the Bodhisats mentioned in the Saddharma Pundarika, and not mentioned in the Lalita Vistara, as attendant on the Buddha are Manju-sri and Avalokitesvara.
The belief in them probably arose out of the doctrine of the older school, which did not deny the existence of the various creations of previous mythology and speculation, but allowed of their actual existence as spiritual beings, and only deprived them of all power over the lives of men, and declared them to be temporary beings liable, like men, to sin and ignorance, and requiring, like men, the salvation of Arahatship. Among them the later Buddhists seem to have placed their numerous Bodhisats; and to have paid especial reverence to Manju-sri as the personification of wisdom, and to Avalokiteswara as the personification of overruling love.
But, being Buddhas, they were supposed to have their Bodhisats; and thus out of the five last Buddhas of the earlier teaching there grew up five mystic trinities, each group consisting of one of these five Buddhas, his prototype in heaven the Dhyani Buddha, and his celestial Bodhisat.
Like the Great Lamas, they bear the title of Rinpotshe or Glorious, and are looked upon as incarnations of one or other of the celestial Bodhisats of the Great Vehicle mythology.