“The noble quality of love should be thought about thus: “One concerned only with his own welfare, without concern for the welfare of others, cannot achieve success in this world or happiness in the next.
How then can one wishing to help all beings but not having loved himself succeed in attaining Nirvana? And if you wish to lead all beings to the supramundane state of Nirvana, you should begin by wishing for their mundane welfare here and now.”
One should think: “| cannot provide for the welfare and happiness of others merely by wishing it. Let me make an effort to accomplish it.” One should think: “Now | support them by promoting their welfare and happiness, and later they will be my companions in sharing the Dhamma.”
Then one should think: “Without these beings, | could not accumulate the requisites of enlightenment. Because they are the reason for practising and perfecting all the Buddha-qualities, these beings are for me the highest field of merit, the incomparable basis for planting wholesome roots, and thus the ultimate object of reverence.” So one should arouse an especially strong inclination towards promoting the welfare of all beings.
And why should love be developed towards all beings? Because it is the foundation of compassion. For when one delights in providing for the welfare and happiness of other beings with an unbounded heart, the desire to remove their afflictions and suffering becomes strongly and firmly established. And compassion is the pre-eminent quality in Buddhahood; it is its basis, its foundation, its root, its head and its chief. ” – Cariyapitaka Atthakata 292