Bodhisattva

Bodhisattvas in Mahayana Buddhism

In Mahayana Buddhism, a bodhisattva has the compassionate determination to aid all beings on their quest for the highest state of development, full enlightenment of a Buddha. This type of motivation is known as bodhicitta ('citta' means mind). Remaining in this world of uncontrolled rebirth (samsara), the bodhisattva has taken the bodhisattva vow to achieve Buddhahood as quickly as possible and thereby be most able to teach Dharma until all beings have likewise achieved enlightenment.
Another common conception of the bodhisattva is one who delays his own entering into Nirvana in order to save all sentient beings out of his enormous compassion. He is on a mission to liberate all sentient beings, and only then will he rest in his own enlightenment.
In brief, simply imagine the bodhisattva as saying, "If I know how to swim, and even one other being cannot, then it is right to remain behind in this world to assist them until they know how to save themselves from drowning".
Mahayana Buddhist philosophy sometimes poses the concept of the bodhisattva in opposition to that of the Śrāvakabuddha (conventionally referred to as an arhat). The arhat is seen as being liberated from samsara (or reincarnation), but he did not choose to save all and every other living being before passing away into Parinirvana, and thus is not a fully enlightened Buddha.
According to many traditions within Mahayana Buddhism, on his or her way to becoming a Buddha, the bodhisattva proceeds through ten, or sometimes fourteen, stages or bhumi. Below is the list of ten bhumis and their descriptions from The Jewel Ornament of Liberation, a treatise by Gampopa, an influential teacher of the Tibetan Kagyu school. Other schools give variant descriptions.
Before a bodhisattva arrives at the first ground, he or she first must travel the first two of the five paths, which are said to correspond to words from the mantra that appears at the end of the Heart Sutra:
1.   the path of accumulation (gate)
2.   the path of preparation (gate).
The ten grounds of the bodhisattva then can be grouped into the next three paths
1.   Bhumi 1 the path of insight (paragate)
2.   Bhumi 2-7 the path of meditation (parasamgate)
3.   Bhumi 8-10 the path of no more learning (bodhi)