Ezekiel 1:19

But while the animals were standing, their wings were lowered. For they could not bear the resonating voice of Almighty God in the heavens, but they stood and marveled; and with their silence, they demonstrated the power of God, who sat upon the firmament.

(Vers. 19 seqq.) When the animals walked, the wheels walked alongside them. And when the animals were lifted up from the ground, the wheels were also lifted up. Wherever the spirit went, the wheels went there too, for the spirit of life was in the wheels. As the animals went, the wheels went, and as they stood, the wheels stood. And when the animals were lifted up from the ground, the wheels were lifted up as well, following them, for the spirit of life was in the wheels. Four animals followed the spirit, and the cloud that was in the spirit. And again, the wheels lifted themselves off the ground, not the animals, but the spirit followed, to show its own will: because the spirit of life was in the wheels. Three, however, are indicated both in the animals and in the wheels, when they stood, when they walked, when they were lifted up, which both the animals and the wheels did in common. For neither could animals that were standing walk on wheels, nor could animals walking on the ground lift themselves on wheels, but of those actions, one was rest, one was motion, and elevation. And secondly it is said, because the spirit of life was in the wheels: so that we should in no way consider the wheels as vessels, which we see in the carts of wagons and chariots, but as living beings, indeed above living beings. For the animal man does not perceive those things that are spirits. Therefore, these wheels, in which the spirit of life was, do all things in order and measure, and they have harmony with animals, following them, and through them, the Holy Spirit; indeed, having skipped the middle, they enjoy the fellowship of the Holy Spirit. All of which, according to the earlier understanding, a wise reader can fit into various interpretations.

"And when the living creatures walked, the wheels also walked beside them; and when the living creatures were lifted up from the earth, the wheels were lifted up together with them." The living creatures walk when holy men understand in Sacred Scripture how they should live morally. But the living creatures are lifted from the earth when holy men suspend themselves in contemplation. And because each of the saints, the more he himself has advanced in Sacred Scripture, the more that same Sacred Scripture advances in him, it is rightly said: "When the living creatures walked, the wheels walked equally with them; and when the living creatures were lifted from the earth, the wheels were lifted together with them," because the divine words grow with the reader; for each one understands them more deeply to the degree that he attends to them more deeply. Hence the wheels are not lifted if the living creatures are not lifted, because unless the minds of readers have advanced to higher things, the divine sayings lie as if in the depths, not understood. For when the words of Sacred Scripture do not arouse the mind of any reader (if the sense of the divine word seems lukewarm to him), and no light of understanding flashes forth in his thought, the wheel is both idle and on the ground, because the living creature is not lifted from the earth. But if the living creature walks, that is, seeks the order of living well, and through the steps of the heart finds how to place the steps of good work, the wheels walk equally with it, because you find as much progress in the sacred word as you yourself have advanced in relation to it. But if the winged living creature has stretched itself forth in contemplation, the wheels are immediately raised from the earth, because you understand that those things are not earthly which you previously believed were spoken in the sacred word according to an earthly manner. And it happens that you perceive the words of Sacred Scripture to be heavenly, if, enkindled through the grace of contemplation, you suspend yourself toward heavenly things. And the wondrous and ineffable power of the sacred word is recognized when the mind of the reader is penetrated by heavenly love. Therefore, because the living creature raises itself to the heights, the wheel flies.