"Suppose there were a pool of water — clear, limpid, and unsullied. A man with good eyesight standing there on the bank would see shells, gravel, & pebbles, and also shoals of fish swimming about and resting. Why is that? It is because of the unsullied nature of the water. In the same way, that a monk with an unsullied mind would know his own benefit, the benefit of others, the benefit of both; that he would realize a superior human state, a truly noble distinction of knowledge & vision: Such a thing is possible. Why is that? It is because of the unsullied nature of his mind."
(Buddha, Udakarahaka Suttas, Anguttara Nikaya 1.45-46, Tipitaka)