Kristina Carroll - Demons Within

Leviathan
charcoal 18 x 24

When he raises himself up, the mighty fear;

Because of the crashing they are bewildered.

The sword that reaches him cannot avail,

Nor the spear, the dart or the javelin.

Nothing on earth is like him,

One made without fear.

He looks on everything that is high;

He is king over all the sons of pride.

-– Job 41:15-32

A great monster of the sea is an image that recurs in many stories. In the myth of Job, God describes Leviathan in detail to Job to remind him of his smallness. It is mentioned several times in Judeo Christian stories but probably originated in the Mesopotamian myth of Tiamat- the great chaos goddess. The running theme is the embodiment of nature and our helplessness against forces we will never control. 

It's interesting that in demonology, the Sea Serpent demon is a power for good and knowledge: (serpents and knowledge...that sounds familiar...)

From the Ars Goetia:

 Forneus is a Great Marquis of Hell, and has twenty-nine legions of demons under his rule. He teaches Rhetoric and languages, gives men a good name, and makes them be loved by their friends and foes.

He is depicted as a great sea monster. He causes men to have a good name and to have the knowledge and understanding of tongues. He makes one beloved by his foes as well as of his friends. He is partly of the Order of Thrones, and partly of that of Angels. His name seems to come from Latin "fornus" or "fornus" (oven). He can take many different forms but mainly prefers his human form.