In one such theological legend the gods and the (evil) spirits, both being sons of the Father-god, inherited from him, respectively, mind and speech; hence the gods got the sacrifice and heaven, while the evil spirits got this earth.

Again, the two entered on the inheritance of their father in time, and so the gods have the waxing moon, and the evil spirits, the waning moon (_ib._ III 2.1.

18; I.7.2.

22).
But what these Asuras or (evil) spirits really are may be read easily from the texts.

The gods are the spirits of light; the Asuras are the spirits of darkness.