A mortal Bodhisattva is one who has manifested himself on earth in human (manushi) form, in a series of incarnations, until such a time as he has acquired sufficient merit and enlightenment (bodhi-jnana) to receive Buddha-hood.
Like Gautama Buddha in his incarnation of the arhat Sumedha,  the Bodhisattva may have been, in a former re-birth, an arhat  bent on his own salvation who, becoming inspired with the desire for Bodhi in order to save mankind, renounced his arhat-ship.
This illumination is called 'Bodhi-chitta'  The aspirant, now aware of his wish for Bodhi, must make the vow that he will re-enter, or continue to remain in, the world of suffering for the sole purpose of saving mankind.
But in order to reach the ultimate goal of Buddha-hood, it is necessary for the Bodhisattva, in one of his incarnations, to meet the reigning Buddha of that kalpa, or epoch, and acquaint him with his desire for Buddha-hood.
He must practice the ten Paramitas which make a Buddha, and continue to accumulate merit in his different re-births, always bearing in mind that his sole aim in becoming a Tathagata is to save all creatures from suffering.
When the future Buddha has reached the last stage of Bodhisattva-hood, and resides in the Tushita heaven, he is free to decide whether he will pass through the intermediary stages of the thirteen Bodhisattva heavens  to reach Nirvana, or will descend to earth and become a mortal Buddha, after which he will enter directly into Nirvana.
The only Manushi-Bodhisattva that is met with in Buddhist art is Maitreya, who has two representations: as Bodhisattva, his present form in the Tushita heaven, and as Buddha, the form he will take when he descends to earth as Manushi-Buddha. (PI. xv, figs, a and b.) All the other Bodhisattva representations are of Dhyani Bodhisattva.
The dhyani-bodhisattva is celestial and is the second 'body' (kaya) in the Tri-kaya or Northern Buddhist Trinity.  He is believed to dwell in the Rupadhatu heaven in the body of absolute completeness (Sambhoga-kaya), in a state of ' reflected spirituality ', that is to say, that it is in this form that the Dharma-kaya (Dhyani Buddha) reveals himself to the Bodhisattva or future Buddhas in the Tushita heaven. Although, according to the Buddhist writings, the name is legion, there are comparatively few Dhyani-Bodhisattva represented in Buddhist art, and these may be divided into two groups — of five and of eight.
The five Dhyani-Bodhisattva correspond with the five Dhyani-Buddhas and differ in many respects from the other celestial Bodhisattva. They are: Samantabhadra, Vajrapani, Ratnapani, Avalokitesvara, and Visvapani.
Certain Northern Buddhist sects that interlink the dogmas of the Tri-kaya and the Tri-ratna  look upon the Dhyani-Bodhisattva as the active creator, Sahgha, product of the union of Buddha (mind) and Dharma (matter).
The Dhyani-Bodhisattva of this group of five have a definite place in the Mahayana system and for a special purpose, that is, to evolve, each in his turn, from his own essence, a material and perishable world over which he is to preside until the advent of the Manushi-Buddha of his cycle.
Three of the Dhyani-Bodhisattva have created worlds, and are now engrossed in worshiping Adi-Buddha, or, according to some, have been absorbed into Nirvana. The present w r orld is the fourth, and there is the fifth yet to come.
In the same way we have:
The second world.
The third world.
Five thousand years after the death of Gautama Buddha, Maitreya will appear as Manushi-Buddha in the fifth world, which will be created by VisVapani (fifth Dhyani-Bodhisattva), who dwells in the Bupadhatu heaven waiting for the fifth cycle, when he will receive active power of creation and evolve the fifth world.
The Dhyani-Bodhisattva is represented dressed in princely garments and wearing the thirteen precious ornaments, which are: a five-leaved crown, an ear-ring, a closely fitting necklace, an armlet, a wristlet, a bracelet, an anklet, a shawl for the lower limbs and one for the upper;
The Dhyani-Bodhisattva may be in company with their Sakti in yab-yum attitude, as well as the Dhyani-Buddhas, who, in that case, are represented like the Bodhisattva and are called ' crowned Buddhas'.
These are also practically the only Bodhisattva popular in Japan. The Bodhisattva in both China and Japan may be either dressed like a Buddha with only the high and complicated ushnisha, indicating his rank, or richly dressed and wearing many ornaments, which, however, do not correspond to the traditional thirteen ornaments quoted above, (v. Kwan-yin and Kwan-non.) </poem>