Sarvadarshanasangraha 16.72

16.72

nanu mukhavikāsādiliṅgād dharṣahetuṃ prasiddhārtham anumāya yatra śabdasya saṃgatigraho yathā putras te jāta ityādiṣu tatrāvaśyaṃ kāryam antareṇaiva śabdasya siddhe ’rthe prāmāṇyam āśrīyata iti cen

If it is objected: Surely where the apprehension of a word's relation occurs through inferring the cause of joy, which is an already established entity, from an inferential sign such as a beaming face—as in [sentences like] “A son is born to you”—there epistemic validity of the word regarding an already established entity must certainly be admitted without any action at all—