[47] Bhikkhus, suppose there were a pool of water — clear, limpid, unturbid. A man with good eyes (cakkhumā), standing on the bank, could see oysters and shells, gravel and potsherds, and shoals of fish, whether moving about or standing still in it. For what reason? Because of the unturbidness of the water, bhikkhus. So too, bhikkhus, it is indeed possible that a bhikkhu with an unturbid mind (citta) will know his own good, or will know the good of others, or will know the good of both, or will realize a superhuman distinction in knowledge (ñāṇa) and vision worthy of the noble ones. For what reason? Because of the unturbidness of the mind, bhikkhus.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.