John 13:2

And when supper was done. By this we must not understand, that the supper was over; for we afterwards find the Jesus again sat down, and gave bread to the traitor. But these words only mean, that all had partook of refreshment, and might be therefore said to have supped. (St. Augustine, tract. 55. in Joan.) --- He knew that he went out from God, and would return to God; but at the same time, he did not leave God, when he went out from him, nor us, when he returns to him. (St. Augustine, as above.) --- And though he went out from God, and returns to him, yet here he condescends to perform the office, not of the Lord God of the universe, but of a man and a slave; (St. Augustine) and this, says St. John Chrysostom, (hom. lxix. in Joan.) that he might tread all pride under foot: doing every thing himself on this occasion, to teach us with what eagerness we ought to perform the duties of humility.