Law and Gospel in a Nutshell (From: letterofmarque.us)

Now Scripture sets forth two kinds of teaching—Law and Gospel. The Law, in condemning sins and setting forth the gravest threats of God, is that hammer (Jer. 23:29) through which God breaks rocks, that is crushes the spirit, renders the heart contrite and humbles it, so that truly and earnestly acknowledging the multitude and magnitude of sins and of the wrath of God over sin, the mind begins to hate and detest sin, to fear the wrath and judgment of God so that it is unwilling to perish eternally under them but sighs and struggles with groaning that it may be freed from them. There the Law indeed has and sets forth promises of life, but on condition of perfect fulfillment… The Gospel, however, teaches that what was impossible for the Law on account of the flesh, God provided by sending His Son (Rom. 8:3). More... http://www.letterofmarque.us/2011/11/law-and-gospel-in-a-nutshell.html