And the likeness of the firmament upon the heads of the living creature was as the colour of the terrible crystal, stretched forth over their heads above.

Wesley's Notes

1:22 Likeness - The appearance or resemblance. As crystal - For splendor, purity, and solidity, all that was above these creatures and wheels was beautiful and very majestic, and 'tis therefore called terrible, because it impressed a veneration upon the mind of the beholders.

Jamieson-Fausset-Brown Bible Commentary

22. upon the heads-rather, "above the heads" [Fairbairn].

colour-glitter.

terrible crystal-dazzling the spectator by its brightness.

Matthew Henry's Concise Commentary

1:15-25 Providence, represented by the wheels, produces changes. Sometimes one spoke of the wheel is uppermost, sometimes another; but the motion of the wheel on its own axletree is regular and steady. We need not despond in adversity; the wheels are turning round and will raise us in due time, while those who presume in prosperity know not how soon they may be cast down. The wheel is near the living creatures; the angels are employed as ministers of God's providence. The spirit of the living creatures was in the wheels; the same wisdom, power, and holiness of God, that guide and govern the angels, by them order all events in this lower world. The wheel had four faces, denoting that the providence of God exerts itself in all parts. Look every way upon the wheel of providence, it has a face toward you. Their appearance and work were as a wheel in the middle of a wheel. The disposals of Providence seem to us dark, perplexed, and unaccountable, yet are all wisely ordered for the best. The motion of these wheels was steady, regular, and constant. They went as the Spirit directed, therefore returned not. We should not have to undo that by repentance which we have done amiss, if we followed the guidance of the Spirit. The rings, or rims of the wheels were so vast, that when put in motion the prophet was afraid to look upon them. The consideration of the height and depth of God's counsel should awe us. They were full of eyes round about. The motions of Providence are all directed by infinite Wisdom. All events are determined by the eyes of the Lord, which are in every place beholding the evil and the good; for there is no such thing as chance or fortune. The firmament above was a crystal, glorious, but terribly so. That which we take to be a dark cloud, is to God clear as crystal, through which he looks upon all the inhabitants of the earth. When the angels had roused a careless world, they let down their wings, that God's voice might be plainly heard. The voice of Providence is to open men's ears to the voice of the word. Sounds on earth should awaken our attention to the voice from heaven; for how shall we escape, if we turn away from Him that speaks from thence.