cittam eva hi saṁsāras
cittam eva hi saṁsāras tat prayatnena śodhayet |
yac cittas tanmayo bhāti guhyam etat sanātanam ||
(Maitrāyaṇīya Upaniṣad: 6.34.3; Śāṭyāyanīya Upaniṣad: 3)
“The citta (mind) itself is saṁsāra [i.e., the condition of one’s citta is the cause of the perpetuation of one’s bondage in saṁsāra]. Purify it with exertion. As is the citta, so one becomes [i.e., one becomes absorbed in, constituted of, and/or identical to the content in one’s citta]. This is the eternal secret.”