John Calvin Commentary John 13:37

"Peter saith unto him, Lord, why cannot I follow thee even now? I will lay down my life for thee." — John 13:37 (ASV)

Why cannot I follow thee now? By these words Peter declares that he was dissatisfied with Christ’s answer. He is aware that he has been warned of his own weakness, from which he concludes that it is his own fault that hinders him from following Christ immediately; but he is not at all convinced of it.

For people are naturally puffed up with confidence in their own value. This expression of Peter shows the opinion we hold from our very birth: that we attribute more to our own strength than we should. The consequence is that those who can do nothing venture to attempt everything, without imploring the assistance of God.