There is the engagement of the heart and affections to sin. This is a mighty hindrance to mortification. The heart is the chief seat and strength of sin. There is a heart union between a sinner and his idols, such as resembles that between a man and his wife; hence, men’s idols are called their lovers, and the backsliding of professors is called adultery and whoredom. Hence, instead of killing their lusts, they love them, and cherish them as their own flesh: to mortify sin were to mortify themselves. Will a man slay the wife of his bosom, the desire of his eyes, or thrust through his intimate friend? Sin is as meat and drink to them, they drink it as the ox does water: it is an air to breathe in, it is as spirits and blood to them: kill me, says the sinner, and restrain me from this or that. When we speak against sin, men take it as if we spoke against themselves; when we cry out against sin, it is to them as if we were reproaching them. Where the eyes are full of sin, a man cannot cease to sin, much less when the heart is full of it. Love strongly unites the heart to sin; there is a league, a covenant of friendship between the heart and sin. Now sin may in a sort keep true to the man for a time, for example, while it is conceiving and growing; but when it is perfected, it brings for death. When one is joined to his idols, there is little hope for him.