It is the universal bridge that saves
All wandering beings from the states of loss,
The rising moon of the enlightened mind
That soothes the sorrows born of the afflictions.
It is the mighty sun that utterly dispels
The misty ignorance of wandering beings,
The creamy butter, rich and full,
That's churned from milk of holy teaching.
Shantideva, A Guide to the Bodhisattva's Way of Life
Chapter 3, Taking Hold of Bodhicitta
Verses 31 & 32 (Shambhala Classics edition)
Very brief commentary. The "it" in these verses (and the subject of the entire third chapter) is Bodhicitta, which broadly translates to the wish to attain enlightenment, or "Buddha Mind" (bodhi = buddha, citta = mind) for the benefit of all sentient beings. That is - not for one's own sake, or at least not for one's own sake alone, but so that one may help liberate others (as well) from the state of suffering that is inherent in the somewhat misdirected or illusory consciousness that is our normal, or everyday, state of experience.
Thus the act of reaching this state, and then helping others by their own paths, to reach this other shore also, is in this way, a profound act of love and caring, helping to extinguish this state of suffering that we generate for ourselves and others, by the very nature of our misunderstanding.