His name is, at this time, written invariably as En-lil.

In the Babylonian theology, he is 'the lord of the lower world.' He represents, as it were, the unification of the various forces whose seat and sphere of action is among the inhabited parts of the globe, both on the surface and beneath, for the term 'lower world' is here used in contrast to the upper or heavenly world.

Such a conception manifestly belongs to the domain of abstract thought, and it may be concluded, therefore, that either the deity belongs to an advanced stage of Babylonian culture, or that the original view of the deity was different from the one just mentioned.

The latter is the case.

Primarily, the ideograph Lil is used to designate a 'demon' in general, and En-lil is therefore the 'chief demon.' Primitive as such a conception is, it points to some system of thought that transcends primitive Animism, which is characterized rather by the equality accorded to all spirits.
The antiquity of the association of En-lil with Nippur justifies the conclusion that we have before us a local deity who, originally the protecting spirit merely, of a restricted territory, acquires the position of 'chief demon' as the town of Nippur grows to be the capitol of a large and powerful district.