Thomas Brooks emphasizes the struggle Christians face with their 'Delilah'—the beloved sin that they cling to despite its destructive nature. He illustrates that just as a garden has a master-weed, each person has a predominant sin that is particularly challenging to overcome. Brooks encourages believers to recognize that God may use painful experiences, such as the loss of a cherished blessing, to motivate them to confront and subdue their besetting sins. He urges Christians to respond to God's discipline with gratitude rather than resentment, understanding that it can lead to spiritual growth and the mortification of sin.

God cures David of adultery, by killing his endeared child. There is some Delilah—some darling, some beloved sin or other—that a Christian's calling, condition, constitution, or temptations—leads him to play with, and to hug in his own bosom. As in a plot of ground that lies untilled, among the great variety of weeds there is usually some master-weed, which is more plenteous and more repulsive than all the rest. So it is also in the souls of men—though there be a general mixture and medley of all evil and corrupt qualities, yet there is some one sin which is usually paramount, which is most powerful and prevalent—which sways and manifests itself more eminently and evidently than any other of them do. So, though the root of sin and bitterness has spread itself over all, yet every man has his inclination to one kind of sin—rather than another. And this may be called a man's besetting sin, his bosom sin, his darling sin. Now, it is one of the hardest works in this world to subdue and bring under control, this bosom sin! Oh! the prayers, the tears, the sighs, the sobs, the groans, the distress that it will cost a Christian before he subdues this darling sin! A man may easily subdue and mortify such and such sins—but when it comes to the master-sin, to the bosom-sin, oh! what tugging and pulling is there! what striving and struggling is there to get off that sin, to get down that sin! Now, if the Lord, by smiting you in some near and dear enjoyment, shall draw out your heart to fall upon the smiting of your master-sin; and shall so sanctify the affliction, as to make it issue in the mortification of your bosom corruption; what eminent cause will you have rather to bless Him, than to sit down and murmur against Him! And doubtless if you are dear to God—God will, by striking your dearest mercy, put you upon striking at your darling sin! Therefore do not murmur, even when God touches the apple of your eye; even when He has snatched the fairest and the sweetest flower out of your bosom.