The vile, unchangeable nature of a fool is portrayed here. He chews on garbage, spews it out in a worse form, and then devours it again. Fools never learn, but continue to be the major consumers of their own foolishness. Fallen man thinks he is wise, but apart from Christ he feeds on the filth vomited from his own sinful nature. Thanks be to God that he has delivered us in Christ from such a dog’s diet and has given us an appetite for the heavenly manna of God’s Word which provides an abundant life.
11 Like a dog that returns to his vomit is a fool who repeats his folly.