kāraṇe kāryopacārād vā upacārasya ca prayojanaṃ tadanyakāraṇebhyo viśiṣṭakāryakāriṇaḥ svabhāvakhyāpanam
Or [it may be explained] through the metaphorical attribution of the effect to the cause, and the purpose of this metaphorical usage is to reveal the nature [of something] as producing a specific effect distinct from [that produced by] other causes.