Sutra 1.7

प्रत्यक्षानमानागमाः प्रमाणानि॥७॥

prat-yaksha-anumaana-agamaa-ha pramaa-naani

Ravi Ravindra translates this as "True knowledge is based upon perception, inference, and valid testimony." We have to start observing all our random thoughts that are not so random after all, since they are based on and are derived from our personal experience.