The heart is the great workshop where all sin is produced before it is exposed to open view. The heart is the mint where evil thoughts are coined, before they are current in our words and actions: “Out of the heart proceed evil thoughts” The heart is the nest in which those hornets breed.
The heart is the source of sinful words as well as sinful thoughts. They were in the heart before they were ever on the tongue. Every sinner conceives at the heart what he brings forth at the mouth. The heart is the vessel of poisonous liquor, the tongue is but the tap to let it out: “Out of the abundance of the heart the mouth speaks.”
The heart is the forge also where all our evil works, as well as words, are hammered out: “Out of the heart proceed murders, thefts, and adulteries, and fornications.” You will say that murders and thefts are hand sins, and that adulteries and fornication belong to the eye and outward parts of the body; but alas! the heart is the womb wherein they are conceived and bred. The outward parts are but the midwives to deliver the mother of those monsters, and to bring them into the world; “An evil man, out of the evil treasure in his heart, brings forth evil things.”
There is no sin but it is dressed in the drawing room of the heart, before it appears on the stage of the life. It is vain to go about a holy life until the heart be made holy.
~ George Swinnock