Charles H. Spurgeon on Psalms 14:1

"The fool," a term in Scripture signifying a wicked man, used also by the heathen philosophers to signify a vicious person, (Heb.) as coming from (Heb.) signifies the extinction of life in men, animals, and plants; so the word (Heb.) is taken Isaiah 40:7, (Heb.) "the flower fadeth" (Isaiah 28:1), a plant that hath lost all that juice that made it lovely and useful. So, a fool is one that hath lost his wisdom and right notion of God and divine things, which were communicated to man by creation; one dead in sin, yet one not so much void of rational faculties, as of grace in those faculties; not one that wants a reason, but abuses his reason. Stephen Charnock.