Paragraph one of St Augustine’s Tractate 56, on John 13:6-10, reads:
When the Lord was washing thedisciples’ feet, He comes to Simon Peter; and Peter says unto Him, Lord, dost Thou wash my feet? For who would not be filled with fear at having his feet washed by the Son of God? Although, therefore, it was a piece of the greatest audacity for the servant to contradict his Lord, the creature his God; yet Peter preferred doing this to the suffering of his feet to be washed by his Lord and God. Nor ought we to think that Peter was one among others who so expressed their fear and refusal, seeing that others before him had suffered it to be done to themselves with cheerfulness and equanimity. For it is easier so to understand the words of the Gospel, because that, after saying,He began to wash the disciples’ feet, and to wipe them with the towel wherewith He was girded, it is then added, Then comes He to Simon Peter, as if He had already washed the feet of some, and after them had now come to the first of them all. For who can fail to know that the most blessed Peter was the first of theapostles? But we are not so to understand it, that it was after some others that He came to him; but that He began with him. When, therefore, He began to wash the disciples’ feet, He came to him with whom He began, namely, to Peter; and then Peter took fright at what any one of them might have been frightened, and said, Lord, dost Thou wash my feet? What is implied in this Thou? And what in my? These are subjects for thought rather than for speech; lest perchance any adequate conception thesoul may have formed of such words may fail of explanation in the utterance.
Here St Augustine argues that Christ must have washed the feet of St Peter prior to the other Apostle’s. As the basis of his argument, St Augustine holds that St Peter could not have had his feet washed after the other apostles’ because St Peter was “the first of the apostles.” He does not use St Peter’s feet being washed first as evidence for or the reason behind the wording of his being “the first of them all;” on the contrary, he uses St Peter’s being “the first of them all” as the reasoning for why St Peter’s feet must have been washed first. Therefore, as St Augustine uses St Peter’s firstness, so to speak, as the basis of his argument, he is implying it to be indisputable fact, as further denoted by the following sentence, which is placed immediately after his basis of Peter’s being “first of them all”:
For who can fail to know that the most blessed Peter was the first of the apostles?
As this question is rhetorical, he is assuming the audience is already aware of St Peter’s being “first of the apostles.” Therefore, had his purpose been to say that St Peter was “first of the apostles” in only the sense of his feet being washed first, this entire paragraph would have been written without need; however, as St Augustine saw need to explain that St Peter’s feet were washed first, he could not be referring to that fact, which needed explaining, in his rhetorical question, as rhetorical questions are used to expresses the perceived indisputable and self-evident, not that which requires explanation.