John Calvin Commentary Matthew 19:30

"But many shall be last [that are] first; and first [that are] last." — Matthew 19:30 (ASV)

And many that are first shall be last. This sentence was added in order to shake off the indolence of the flesh. The apostles, though they had scarcely begun the course, were hastening to demand the prize. And such is the disposition of almost all of us, that, when a month has elapsed, we ask, like soldiers who have served their time, to receive a discharge. But Christ exhorts those who have begun well (Galatians 3:3; Galatians 5:7) to vigorous perseverance, and at the same time gives warning, that it will be of no avail to runners to have begun with alacrity, if they lose courage in the midst of the course. Likewise, Paul also warns us that not all who run obtain the prize (1 Corinthians 9:24), and in another passage he exhorts believers, by referring to his own example, to:

forget those things which are behind, and press forward to the remaining portion of their course, (Philippians 3:13–14).

As often, therefore, as we call to mind the heavenly crown, we ought, as it were, to feel the application of fresh spurs, that we may not be more indolent for the future.