The essence of Mahayana Buddhism is bodhicitta; the basis of bodhicitta is compassion. Without compassion, there can be no bodhicitta.

What allows us to develop compassion? It is precisely suffering. When we truly understand all sentient beings have to undergo great suffering in samsara, we can be comforted in knowing there is a law of cause and effect. We know that all of our suffering is created by negative deeds we committed in past lives and that we must bear the consequences. But other sentient beings may not understand these concepts; they perpetuate in hatred and resentment which bind them further in suffering. Seeing this, we easily develop empathy and compassion, sincerely hope all sentient beings can be freed from suffering, and willingly trade our happiness for their suffering — this is compassion.

- Quote from Are You Ready For Happiness? Don't Let the Paper Tiger Scare You Off, "How to Face Suffering"