now the least mighty -- yet were they very great beside the men of those days -- are cold as is the nature of snakes and serpents , and of them a many having wings go with the uttermost noise and speed ; but the mightier are hot and very heavy and slow-going , and some belch flame , and fire flickereth beneath their scales , and the lust and greed and cunning evil of these is the greatest of all creatures : and such was the foaloke whose burning there set all the places of his habitation in waste and desolation .