Sāṃkhya Kārikā verse 4

dṛṣṭam-anumānam-āpta-vacanaṃ ca sarva-pramāṇa-siddhatvāt |
trividhaṃ pramāṇam-iṣṭaṃ prameya-siddhiḥ pramāṇāt-hi ||

dṛṣṭa - seenanumāna - inferenceāpta - a credible or authoritative personvacana - the act of speaking , utterance; statement, declarationsarva - allpramāṇa - right perception, a correct notion; a means of acquiring; measure, scale, standardsiddhi - accomplishment, performance, fulfilment, attainment, successtrividha - three foldiṣṭa - wished, desired; liked, beloved; chosenprameya - to be ascertained or proved; to be measured; the thing to be proved or the topic to be discussed

Commentaries and Reflections

Commentary by Paul Harvey:

The means to right perception involves
direct observation,
inference and
authentic authority.