Ezekiel 1:14

But the burning coals and the lamps running among the animals are interpreted from that place of Isaiah: And the fire shall eat the flesh as the grass, and I will sanctify them in the burning fire (Isaiah 5:24). And it is written elsewhere: Burning coals shall fall upon them (Psalm 140:11). And against deceitful lips, it is said in another psalm: 'What shall be given to you, or what shall be added to you, to a deceitful tongue? Sharp arrows of the powerful, with coals of desolation.' (Psalm 119:3-4).

(Vers. 13, 14.) And the likeness of the creatures, and their appearance was like burning coals of fire, and like the appearance of torches. This was the vision running among the creatures, a gleam of fire, and lightning coming forth from the fire. And the creatures went and returned like the flashing of lightning. LXX: And in the midst of the creatures a vision like burning coals of fire, like the appearance of torches running among the creatures; and a gleam of fire, and lightning came forth from the fire.

There follows: And the living creatures went and returned in the likeness of flashing lightning. Since it was said above, "They did not turn back when they walked," for what reason is it now said, "The living creatures went and returned"? These statements seem very much contrary to each other, because they went and did not return, and they went and returned. But we recognize more quickly how this should be understood if we carefully distinguish the two lives, namely the active and the contemplative. For we can remain fixed in the one, but we are by no means able to hold the mind attentive in the other. For when we leave behind our sluggishness and rouse ourselves to the pursuit of good work, where else do we go but to the active life? From which we should by no means turn back afterward, because whoever returns after it to the sluggishness of negligence, to the wickednesses of depravity which he had left behind, undoubtedly does not know how to be a heavenly creature. But when we rise from the active life to the contemplative, because the mind cannot long stand in contemplation, but sees everything that it perceives of eternity through a mirror and in an enigma, as if furtively and in passing, the soul, repelled by its own weakness from the immensity of such great loftiness, slips back into itself. And it is necessary that it return to the active life and exercise itself continually in the practice of good work, so that when the mind cannot rise to contemplate heavenly things, it may not refuse to do whatever good things it can. And so it happens that, aided by its own good actions, it rises again to contemplation toward higher things and receives the nourishment of love from the pasture of contemplated truth. […]

And the living creatures ran,....

They ran into the lower world, to do what was to be done there; but, when they had done it, they returned like flash of lightning to the upper world again, to the beatific vision of their God, which they could not with any patience be longer from than their service did require.