One of the unique contributions of Mahayana Buddhism has been the development of the concept of the bodhisattva, an individual who has won release from suffering and the painful rounds of rebirth, but who chooses to remain in this world, the world of samsara, in order to help others.

Bodhisattva is a Sanskrit word (Pali bodhisatta) literally meaning "enlightenment being". In Mahayana Buddhism, a bodhisattva is a being who seeks buddhahood though the systematic practice of the perfect virtues (paramita) but renounces complete entry into nirvana until all other beings are saved. In this the bodhisattva is motivated by compassion (karuna), supported by wisdom (prajna). A bodhisattva is willing to take on the suffering of all other beings, and to transfer karmic merit to others. The bodhisattva undertakes voluntary rebirth through compassion for those still suffering in the world of samsara.

The ten perfections (paramita) which are to be cultivated by those pursuing the bodhisattva ideal are generosity, morality, renunciation, wisdom, energy, patience, truthfulness, determination, loving-kindness and equanimity.

Those who aspire to become bodhisattvas seek to generate bodhicitta. This is a Sanskrit word which literally means "awakened mind" but it is also sometimes rendered as "wisdom heart" in order to convey the equally important and complementary virtues of wisdom and compassion. The way of a bodhisattva begins with arousing the thought of enlightenment (bodhicitta) and taking the bodhisattva vow (pranidhana).

Prior to this development in the Mahayana, the principal spiritual ideal to which Buddhists aspired was that of the arahant (Sanskrit arhat). The arahant, with the guidance of an enlightened teacher, all passion and desire to at last enjoy nibbana. Unlike bodhisattvas, arahants seek release for themselves alone, although they put their remaining time in this world to good effect by teaching the Dhamma. The new thinking in Mahayana considered the goal of the arahant to be too narrow and ego-oriented.

The notion of the bodhisattva was already present in earlier Buddhism. In the Jatakas, the stories of the previous existences of the Sakyamuni Buddha, he is referred to as the bodhisattva, the Buddha-to-be. In Mahayana, there was a new focus on future buddhas, who have for a long time already existed as bodhisattvas.

In the Mahayana there are two kinds of bodhisattvas - earthly and transcendent. Earthly bodhisattvas are persons who are distinguished by their compassion and altruism as well as by their striving towards enlightenment. Transcendent bodhisattvas have actualised the paramitas and attained buddhahood but have postponed their entry into complete nirvana. They have perfect wisdom and are no longer subject to samsara. They appear in various forms in order to help others on the path to liberation.

The most important of these transcendent bodhisattvas are Avalokitesvara, Manjusri, Ksitigarbha, Mahasthamaprapta and Samantabhadra.

Followers of Mahayana Buddhism observe a discipline (bodhisattva-sila), of which the ten most important rules are to refrain from killing, stealing, sexual misconduct, lying, the use of intoxicants, gossip, boasting, envy, resentment and ill will, and slandering the three jewels of Buddhism, ie the Buddha, the Dhamma and the Sangha.

The first step on the way of a bodhisattva is the bodhisattva vow (pranidhana), which can be taken by any Buddhist, laypersons as well as monks and nuns. It includes the firm resolution to attain enlightenment oneself and to liberate all beings by leading them to nirvana.

Probably the best known of the bodhisattvas is Avalokitesvara, also known as Kuan Yin to the Chinese, Kannon to the Japanese, and Chenresig to the Tibetans. One interpretation of the name Avalokitesvara is "the lord who looks down", and another is "the one who hears the crying out of the world". Avalokitesvara embodies compassion, and is sometimes called Mahakaruna, "great compassion". Throughout the world, millions of people appeal to Avalokitesvara’s limitless compassion, especially at times of great danger. In Buddhist art, Avalokitesvara is shown in many ways. Frequently he is shown with a thousand arms, a thousand eyes, and eleven faces. Usually adorning his head is a small image of the Buddha Amitabha. He often holds a blue lotus blossom in his hands (because of which he is sometimes called Padmapani, "lotus holder"), a rosary, and a vase of nectar. The many arms symbolise his ability to work for the welfare of sentient beings in a way which is appropriate to any situation. Sometimes he is shown with an eye in the palm of each of his many arms, symbolises his ability to see the many problems in the world.

Manjusri is also known as to the Chinese as Wen Shu Shih Li (Wen Shu in short) and Monju to the Japanese. Manjusri is often linked to Avalokitesvara because between them they embody the two most important virtues of the bodhisattva- Avalokitesvara for compassion, and Manjusri for wisdom. The name Manjusri literally means "who is noble and gentle". He is usually depicted as seated on a lotus blossom and with a wreath of lotus blossoms and a crown of five jewels on his head. He carries a sword and a book. The book stands for wisdom and the sword dispels the darkness of ignorance.

Ksitigarbha is also known as Ti Tsang to the Chinese, or Jizo to the Japanese. The literal meaning of Ksitigarbha in Sanskrit is "womb of the earth". His Chinese name could be rendered as "earth store". He is venerated as a saviour from the torments of hell, and helper of children who have died. Sometimes he is also regarded as a protector of travellers. He is the only bodhisattva who is portrayed as a monk, although he also has the urna, one of the 32 marks of perfection, on his forehead. His attributes are the wish-fulfilling gem (cintamani) and a monk’s staff with six rings, signifying that he stands by all beings in the six realms of existence.

Samantabhadra (Pu Hsien to the Chinese and Fugen to the Japanese) is venerated as the protector of all those who teach the dharma and as the embodiment of the wisdom of essential sameness (the unity of sameness and difference). His symbols are the wish-fulfilling jewel and the lotus, or else the scroll on which the text of his meditation sutra is written. Like Avalokitesvara, Samantabhadra often takes a feminine form in Chinese and Japanese Buddhism. She personifies love, sacred activity, virtue, diligent training and patience. Samantabhadra is also often associated with Vairocana Buddha, one of the five "transcendent buddhas".

Mahasthamaprapta (Ta Shih Chi in Chinese) is another important bodhisattva, who is believed to bring the knowledge of the necessity of liberation. He is often shown with a pagoda in his hair, and is strongly associated with Amitabha Buddha.

The bodhisattvas are traditionally associated in groups of three.

Samantabhadra is often seen riding on a white elephant on one side of the Sakyamuni Buddha with Manjusri on the other side riding on a lion. Samantabhadra and Manjusri also form a trinity with Avalokitesvara, or Kuan Yin.

Mahasthamaprapta is frequently depicted on the right hand side of Amitabha Buddha, with Avalokitesvara on the other side.

Above arahants are fully-fledged Buddhas who have achieved supreme enlightenment (samma sambodhi). Sakyamuni Buddha is the Buddha of our particular era, but there have been others before him and there will be others to come.

In the Chinese pantheon, there are a number of Buddhas, classified into groups such as "transcendent buddhas" and "earthly buddhas". Some of the most important of these are:

Bhaisajyaguru, better known as the Buddha of Medicine or the Master of Healing. He is believed to be helpful in curing illness, and in warding off calamities such as famine, drought and plague. He is often found in a trinity with Sakyamuni Buddha and Amitabha Buddha. His symbols are the medicine bowl or the pagoda.

Amitabha Buddha, the Buddha of the Pure Land (Sukhavati) or Western Paradise. Followers of Amitabha Buddha believe that they and all other beings will be able to attain the Pure Land if only they have sufficient faith in calling on the name of Amitabha.

The development of the bodhisattva ideal gave a new direction to Buddhism. As time went by, the virtue of compassion (karuna) became increasingly highly-regarded, because it is the motivating quality of the bodhisattva. We now see Buddhist organisations that are active in welfare work and in providing support for hospitals, schools and other social institutions. We also see lay Buddhists taking the ideal of the bodhisattva as their goal, as this provides an opportunity to practice Buddhism at a high level without necessarily renouncing the world to become a monk or nun.