John Calvin Commentary Jude 1:6

"And angels that kept not their own principality, but left their proper habitation, he hath kept in everlasting bonds under darkness unto the judgment of the great day." — Jude 1:6 (ASV)

And the angels. This is an argument from the greater to the less, for the state of angels is higher than ours; and yet God punished their defection in a dreadful manner. He will not then forgive our perfidy if we depart from the grace to which He has called us. This punishment, inflicted on the inhabitants of heaven and on such superior ministers of God, should surely be constantly before our eyes, so that we may never be led to despise God’s grace and thus rush headlong into destruction.

The word ἀρχὴ in this place can be aptly understood as beginning as well as principality or dominion. For Jude intimates that they suffered punishment because they had despised the goodness of God and deserted their first vocation. An explanation immediately follows, for he says that they had left their own habitation; for, like military deserters, they left the station in which they had been placed.

We must also notice the atrocity of the punishment which the Apostle mentions. They were not only free spirits but celestial powers; yet they are now held bound by perpetual chains. They not only enjoyed the glorious light of God, but His brightness shone forth in them, so that from them, as if by rays, it spread over all parts of the universe; now they are sunk in darkness.

However, we are not to imagine a specific place in which the devils are confined, for the Apostle simply intended to teach us how miserable their condition is since they apostatized and lost their dignity. For wherever they go, they drag their own chains with them and remain involved in darkness. Their extreme punishment is, in the meantime, deferred until the great day comes.