Hardness of heart is either total and absolute, or partial and comparative only.
Total hardness is either natural and universal, or judiciary in some particular individuals.
Natural hardness is the blindness or obstinacy of the heart in sin by nature, which is not to be cured by the use or application of any outward means: “Hardness and impenitent heart,” Rom. 2:5. This is that heart of stone which God promises in the covenant to take away by the efficacy of his almighty grace, Ezek. 36:26. Where this hardness abides uncured, unremoved, there sin is absolutely in the throne.
