From John Calvin’s Golden Booklet of the True Christian Life:
“Even the greatest saints, though realizing that they can only be strong in the grace of God and not in themselves, are nevertheless more sure than they ought to be of their own bravery and persistence, unless he leads them by the trials of life into a deeper knowledge of themselves. This proud idea even induced David to say: ‘In my prosperity I said, I shall never be moved; Lord, by thy favor thou has made my mountain to stand strong. Thou didst hide thy face, and I was troubled.’
For he confesses that prosperity had so stupefied and benumbed his senses that he disregarded the grace of God on which he should have depended, relied on himself instead, and imagined that he could not fall.”