Bhagavatapurana 3.26.22

3.26.22

svacchatvam avikāritvaṃ śāntatvam iti cetasaḥ /
vṛttibhir lakṣaṇaṃ proktaṃ yathāpāṃ prakṛtiḥ parā //

22. Clearness, absence of change and serenity form the characteristics of chitta and thus the definition is given with reference to its states; and it is of the nature of water in its pure unmixed state (before coming in contact with earth and exhibiting changes such as foam, waves, and the like i. e. it is like the water sweet and soothing in its natural state.)