The quote, "the spirit is willing, but the flesh is weak" is from the Bible.

Mark 14:38

"Keep watching and praying that you may not come into temptation;

the spirit is willing, but the flesh is weak."

Matthew 26:41 (King James): Watch and pray, that ye enter not into temptation: the spirit indeed is willing, but the flesh is weak.

That quote is from the character Wilkins Micawber in Charles Dickens' novel David Copperfield. Micawber is a jovial, well-intentioned character who often finds himself in financial difficulties.

The Willing Flesh was created in 1956.

The Flesh Is Weak was created in 1957.