Ezekiel 1:7

This seems added by way of explanation. Since Ezekiel has spoken of their human form, he adds that their feet were straight, although he calls them round or like those of a calf. I refer the straightness not to the feet only but also to the legs. It is therefore just as if he had said that these animals stood as men do. For we differ from the brutes, who look down towards the ground. As the poet appositely remarks, when he commends the singular favor which God has conferred upon man,

Man looks aloft, and with erected eyes
Beholds his own hereditary skies. (28)

The Prophet now signifies the same thing, when he says that the animals had straight feet. He asserts that they had not anything akin to brutes, but rather to the appearance or likeness of man. He says that their feet were round, and this seems to indicate their agility or the variety of their movements, as if he had said that their feet were not confined, to any one direction, but wherever God impels them they move easily, since their feet are round. If any of us wishes to turn either to the right or the left, he will feel himself to be contending with nature, if he attempt at the same time to walk backwards; if however his feet were round, or of the form of calves’ feet, he could easily move in any direction. Agility of this kind then seems pointed at in the animals. As to the sparks which shone like polished brass or steel, we know that this similitude often occurs in Scripture, for whenever God wishes to render his servants attentive, he proposes new figures which may excite their admiration. This very thing happened to our Prophet, because if the usual fleshy color had appeared in these animals, this perhaps would have been neglected: even the Prophet had not considered the meaning of the vision with sufficient attention. But when he saw the glistening thighs and sparks shining in every direction, as if from polished steel, then he was compelled to apply his mind more attentively to this vision, Now, therefore, we see why he says that the appearance of the legs was like polished steel, and that sparksglittered on them