“My favorite quotation from Shantideva's book is: 'As long as space endures, as long as sentient beings remain, until then, may I too remain and dispel the miseries of the world.'” -Dalai Lama

Whereas all other virtues are like plantain trees,
In that they are exhausted once they bear fruit,
The enduring celestial tree of bodhicitta
Is not exhausted but increases by bearing fruit.

-Shantideva, Guide to the Bodhisattva’s Way of Life

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The quality of mercy is not strain’d,
It droppeth as the gentle rain from heaven
Upon the place beneath. It is twice blest:
It blesseth him that gives and him that takes.

-William Shakespeare, Merchant of Venice

Bodhicitta is the aim to bring happiness to all sentient beings and to relieve them of suffering.  It is a major element of enlightenment and the primary motivation of a bodhisattva.