John Calvin Commentary James 1:4

"And let patience have [its] perfect work, that ye may be perfect and entire, lacking in nothing." — James 1:4 (ASV)

But let patience have her perfect work. As boldness and courage often appear in us and soon fail, he therefore requires perseverance.

“Real patience,” he says, “is that which endures to the end.” For work here means the effort not only to overcome in one contest, but to persevere through life.

This perfection may also be referred to the sincerity of the soul, meaning that people ought willingly and not insincerely to submit to God. However, since the word work is added, I prefer to explain it as constancy.

For there are many, as we have said, who show heroic greatness at first, but shortly after grow weary and faint. He therefore instructs those who would be perfect and entire to persevere to the end.

But what he means by these two words, he afterwards explains as referring to those who do not fail or become weary. For those who, being overcome in patience, are broken down, must necessarily be weakened by degrees and eventually fail completely.