The story of Maitreya begins incalculable ages in the past during the time of Buddha Ratna-chattra. One of his disciples was the monk Sthiramati, who had infinitely more concern for the welfare of others than he did for himself. He would often forsake taking food until he had established a vowed number of beings on the path of pure moral discipline, concentration and wisdom. So strong was his dedication to others' happiness and so radiant his kindness and love (Skt Maitri) that even the gods of heaven praised him, giving him the title "Loving One", or Maitreya. Buddha Ratna-chattra predicted that in all his future rebirths as a bodhisattva he would be known by this name and that his fame would spread far and wide.
In addition to love, one of the main practices of Maitreya was the Seven-Limb puja. This powerful method for countering the delusions, purifying negativity and accumulating meritorious energy is an integral part of the Mahayana Buddhist practice (prostration, offering, declaring non-virtue, rejoicing, entreating the guru-buddhas to remain, requesting teachings and final dedication). Through sincere performance of these seven limbs Maitreya eventually achieved full enlightenment.
Although Maitreya realized buddhahood before Shakyamuni, he honored Shakyamuni as his guru and held him in highest esteem. One way portraying Maitreya shows him adorned with a stupa on the crown of his head, the stupa symbolizes Shakyamuni and its position on Maitreya demonstrates supreme respect. When Shakyamuni appeared in this world as the fourth founding Buddha of the present age, Maitreya manifested as one of his disciples (along with Avalokiteshvara, Manjushri and others) to demonstrate how the bodhisattva path should be followed.
Maitreya is often figured gathered around Shakyamuni to listen to his teaching of the Universal Vehicle discourses. He and Manjushri are often paired there in dialogues, or in alternating interlocution of the Buddha.
This scripture that Maitreya revealed to Asanga have detailed teachings about the buddha-nature(vajra nature) or buddha-potential, existing within the minds of all living beings. This potential enables ordinary beings to be transformed into fully awakened buddhas.
Here's an extract from this scripture:
Under the floor of some poor man's house lies an un-corroded treasure,
But because he does not know of its existence
He does not say that he is rich.
Similarly, inside one's mind lies truth itself, firm and unfading,
Yet, because beings see it not,
They experience a constant stream of misery.
The pauper with a treasure buried under his shack
Does not say he has a treasure,
For he knows it not:
Likewise, the treasure of truth lies within the house of the mind,
Yet we live impoverished through lack of it.
Therefore the seers take a pure birth into the world,
So that this [treasure] may be made known.
During the Life of Krishna
Lord Maitreya incarnated and manifested as the famous Rishi who was the greatest disciple of Krishna and is found throughout the Vedas.
In the Srimad Bhagavatam Canto 2 chapter 7
Text 49-50:
O gentle one, please tell us here about the new things Vidura discussed with Maitreya [a famous rishi] who is so full of transcendental knowledge and anything else he asked His grace and got answered from him back then. Why did Vidura actually give up his activities and his associates and why did he return home afterwards?"
Saunaka Rsi said: Let us know, please, what topics were discussed between Vidura and Maitreya, who talked on transcendental subjects, and what was inquired by Vidura and replied by Maitreya. Also please let us know the reason for Vidura's giving up the connection of his family members, and why he again came home. Please also let us know the activities of Vidura while he was in the places of pilgrimage.
O Maitreya, heartening the good fortune of everyone, please describe us of all topics the essence: the talks about the Lord that like the nectar of flowers are the glorious of pilgering. Please recite all pertaining to the transcendental superhuman activities accomplished by the Lord through His acceptance of incarnations centering on the maintenance of the created of His universe. '
Srî Suka said: 'Thus the great sage His lordship Maitreya as requested did Vidura the great honor to expound on this to him for the ultimate welfare of all.
Srî Maitreya said: ' All blessings to you, o good one, your asking me for the sake of all is proof of the goodness of your mercy to broadcast the glories of the soul in the Transcendental of the mind in this world.
It does not astonish me to find you in this, without deviation of thought, in acceptance of the Supreme Personality our Lord, O Vidura, as you were born from the semen of Vyâsa. You are the one born from the curse of the powerful sage Mândavya Muni as the incarnation of Yamarâja, the controller of death, from the maidservant of the brother [Vicitravirya] and the son [Vyâsadeva] of Satyâvatî . You, your goodness, are recognized as one of the eternal associates of the Supreme Lord, who, on His return to His abode, has given me the knowledge and order to instruct you. Therefore I shall describe to you systematically the pastimes pertaining to the Supreme Lord His greatly extended external energy for the maintenance, creation and dissolution of the cosmic reality.
The one and Supreme Lord was there prior to the creation as the soul of the living entities mastering the self and being merged in its longing He is seen as being different with different characteristics. At that time He was with all of these not seen as the undisputed proprietor in the cosmic creation and was thought to be nonexistent with His plenary portions unmanifested to the power of His manifest internal potency. The external energy is of the perfection of the seer, that is the Lord, seen as the power of the operation of cause and effect and is called mâyâ [or the deluding influence of matter], o fortunate one, of which the Almighty has constructed this world. The Supreme Living Being, by the incarnation of the Original Person, which is the plenary expansion of the original soul, impregnated through the seeds of the living entities, under the influence of time, the external energy in being the Transcendence to the modes of mâyâ. Thereafter came about, by the interaction of time, from the unmanifested, the sum total of unalloyed goodness that could root in the embodied to manifest the supreme light of complete universes. That sum total, which must as well be considered a plenary expansion of the soul to the mode and time, differentiated as the reservoir of the becoming entities into the many different forms of the range of sight of the Personality of Godhead and of this one saw the generation of its falsification.
The great of the causal truth [maha-tattva], transformed into the material reality of false ego, gave rise to effects, the material cause and the doer and thus sprouted to the self its senses the material ingredients of the three kinds of false ego known as the modes of goodness, passion and ignorance that one finds on the mental plane. By transformation from this reality, through interaction with the mode of goodness, the mind generated and also through this interaction the phenomenon of all the godly came about that are the source of material knowledge. The senses are certainly of the mode of passion and thus are its predominating knowledge and fruitive activities likewise. From slowness then the subtle sense objects [of sound] were realized and from that the sky can be considered the symbolic representation of the Supreme Soul. The Supreme Lord glancing over the sky as [cyclic] time mixing the external energy, created from the touch of contacting with the sky the air. The air, also transformed by the extremely powerful sky then gave rise to the lightening [bio-electricity] of sense perception and thus the light of the world to see. The interacting of the air and the glance of the Supreme with that electricity created of the time mix of the material energy the taste [of life] in water. Electrified water subsequently, due to the transforming glancing over by the Supreme of the earth, achieved to the quality of smell in the partial mixture of cyclic [eternal] time with the external energy.
Beginning from the sky, all the material elements, and o gentle one, the great number of their superior and inferior qualities, you may see as [due to] the final touch of the Supreme. The godly of all these physical elements are part and parcel of Vishnu and are embodied as part and parcel of the cyclic of time to the external energy. Because of their different duties being not capable [of the complete] they utter fascinating prayers to the Lord. The godly ones said: "Our obeisances to your lotus feet, o Lord, in distress we surrendered us to them as they are the protecting umbrella giving shelter to the great sages that forcibly throw out all the great miseries of material life completely. O Father, because of the fact that in this material world, o Lord, the individual souls are always embarrassed by the three miseries [born from oneself, others and nature] they are never happy, but gaining to your (Super-)soul, o Supreme One, to the shade of your lotus feet, they are full of knowledge and find shelter. At every step taking shelter of the feet of pilgrimage, they who search after Your lotus like face find its protection carried by the wings of the vedic hymns of the sages at the best of rivers [the Ganges], whose clarity of mind liberates one from the reactions to sin. The meditation that with belief and from simply hearing and in devotion as well is cleansing the heart by the strength of the knowledge of detachment, obliges the pacified to go for the sanctuary of Your feet. For the birth in, the fortitude with and internalization to the paining material reality, let us all take shelter of the incarnations of Your lotus feet that are the refuge, o Lord, that awards the courage of the devotees with remembrance. Because of getting entangled and thus being of the material body in the mind of I and mine, we as persons are immersed in undesirable eagerness and see You as being far from us although we are present in Your [Universal] body; let us therefore worship Your lotus feet, o Lord. They [Your feet] are certainly there for the ones under the material influence who from their sense-perception are alienated from the internal vision, o Supreme One, and therefore can never see Your greatness, but to those who do see your divine action there is the enjoyment of the transcendental. O Lord, those who are of a serious attitude simply by drinking of the nectar of the talks attain to enlightened devotional service, the full purport of renunciation and the intelligence in which they quickly achieve the spiritual sphere where there is no fear [Vaikuntha]. For others of the transcendental realization of unifying by the strength of powerfully conquering over the material nature, You are also that one pacifying original person they enter into, but for them it is a lot of work whereas that is not so for the ones who serve You. O Original One, therefore we are [now] all Yours; as for the sake of the creation of the world we were created one after another and in the past were separated by our own actions to the three modes and thus, in the network of our own pleasures, couldn't manage in respect of You. O Unborn One, direct us in our efforts of offering to You at the right time so that we can share as well the meals as the amenities for You and surely also all the ones we live with, and that we, with our sacrifices, therewith may enjoy the food in peace. O Lord, You are of us, the god-conscious and our orders, the one and the same original founder; You o Lord, although You are unborn, are to the energy, the cause of the material modes and the activities indeed as the initiated seed for begetting the variety. O Supreme Soul, tell us what we, who were all created from and for the totality of the cosmos, should do for You, and specifically grant us the vision of your personal plan and the ability to work, o Lord, and act according our different departments [status orientations and their transcendence].
Text 42:
Srî Suka said: 'He [Maitreya], the chief among the sages so well known with the stories [Purânas], thus being questioned by the chief of the Kuru's felt sufficiently enriched and satisfied and thus being stimulated on the topics about the Supreme Lord, he smilingly replied Vidura.
Srî Sukadeva Gosvâmi said: Thus the chief of the sages, who was always enthusiastic about describing topics regarding the Personality of Godhead, began to narrate the descriptive explanation of the Purânas, being so infused by Vidura. He was very much enlivened by speaking on the transcendental activities of the Lord.
Chapter 8 Canto 3
Text 3:
The son of Brahmâ [Sanat-Kumâra] inquired, heading the great sages [the four boy-saints, the Kumâra's], exactly like this for the truth about the original Personality with Lord Sankarsana [the first plenary portion and companion of the Lord] who undeterred of knowledge resides at the basis of the Universe.
Some time ago, being inquisitive to know, Sanat-kumâra, the chief of the boy-saints, accompanied by other great sages, inquired exactly like you about the truths regarding Vâsudeva, the Supreme, from Lord Sankarsana, who is seated at the bottom of the universe.
Chapter 10
Text 11
Maitreya said: 'It is the source of the interactions to the modes of nature, it is undivided and unlimited and the instrument of the Original Person who created the material life of the soul through His pastimes.
Maitreya said: Eternal time is the primeval source of the interactions of the three modes of material nature. It is unchangeable and limitless, and it works as the instrument of the Supreme Personality of Godhead for His pastimes in the material creation.
As a Bodhisattva, Maitreya appears in many sutras. In the Larger Sukhavati Vyuha he is shown the Pure Land of Amitabha by Shakyamuni Buddha. In this sutra Maitreya is called by one of his other names, Ajita (unconquered). He also appears in the Gandhavyuha sutra. According to the tradition, Maitreya is also the author of some commentarial work, known as the Five Books of Maitreya. These include Abhisamaylankara, a brilliant summary of the Perfection of Wisdom Sutra in 25,000 lines. Modern scholars attribute these five works to Asanga or Maitreya-natha, however, there's no reason in principle, though, why the writer should not have been directly inspired by Maitreya to compose these works. Tradition has that through deep meditation Asanga had a vision of the Tushita devaloka during which he received from Maitreya the teachings contained in the Five Books.
Asanga had been experiencing difficulty in gaining and unmistaken understanding of the Perfection of Wisdom sutras and decided that only from Maitreya could he receive the instructions he needed. He therefore entered into intensive retreat in hopes of gaining a direct vision of this Buddha.
After three years of intensive retreat with no success he quit this retreat. On his way back home he saw an old man trying to remove a huge stone by brushing it with a feather. Asanga took this as a sign that with enthusiastic perseverance, anything could be accomplished, so he reentered his retreat. More years passed, without results. But each time Asanga gave up he would encounter someone doing an impossible task, and thus he would be re inspired again. But after 12 years with no results, Asanga gave up his practice for good. This time on his way home, he saw a starving dog on the ground, its wounds being eaten by maggots. Moved by compassion for the dog and maggots, he cut off a piece of his own flesh and bent down to transfer the maggots to the meat with his tongue so he would not hurt the maggots. He closed his eyes, but although he leaned over very far, he felt nothing. When he opened his eyes to see what was wrong, the dog had disappeared and in its place stood Maitreya in all his glory.
Asanga was shocked and asked: "Where were you all those years I was meditating in the cave?" Maitreya replied that he had been there next to him all that time and only delusions had prevented Asanga from seeing him. Asanga's compassionate act removed the veil of those delusions.
Maitreya took Asanga and transported him to Tushita. They spent the morning there, during which Asanga received detailed instructions from Maitreya on the Perfection of Wisdom sutras in the form of five texts. These are:
Ornament of Realizations
Ornament of Universal Vehicle Scriptures
Analysis of the Jewel Matrix, or Peerless Continuum (Uttaratantra)
Discrimination between Center and Extremes
Discrimination between Phenomenon and Noumenon