法界次第初門 1.258

1.258

次四禪而辨四無量心者，四禪但是自證禪定功德，而未有利他之功，故樂大功德者，當憐愍一切眾生，修慈、悲、喜、捨四無量定。此四通名無量心者，從境以得名，以所緣眾生無量故，能緣之心亦隨境無量，故悉受無量心名。

As for expounding the four immeasurable minds after the four dhyānas: the four dhyānas are merely the virtues of self-realized meditative absorption and do not yet possess the merit of benefiting others. Therefore, those who delight in great virtue should pity all sentient beings and cultivate the four immeasurable meditative absorptions of loving-kindness, compassion, sympathetic joy, and equanimity. That these four are collectively called 'immeasurable minds' is derived from their objects: because the sentient beings that are taken as objects are immeasurable, the minds that take them as objects likewise become immeasurable in accordance with the objects; hence they all receive the name 'immeasurable minds'.