The System of the Vedanta according to Badarayana's Brahma-Sutras and Cankara's Commentary c7.s3.t4.2

c7.s3.t4.2

At the end of the Kalpa, therefore, the earth becomes water again; water, fire; fire, air; air becomes Âkâça, and Âkâça re-enters Brahman. This view is likely to throw some light on the scientific motive of the teaching of the gradual evolution and absorption of the elements, as to which we have no other information: the observation that solids dissolve in water, that water turns into steam through heat, that the flames of fire flicker out into the air (Chând. 4, 3, 1: *yadâ vâ' agnir udvâyati, vâyum eva api-eti*), air, according to the altitude, rarifies more and more into empty space, might lead us to the gradual progression of the dissolution of the world, and by inversion to its opposite, the creation of the world.⁹⁷